CHI PLAY '19: Proceedings of the Annual Symposium on Computer-Human Interaction in Play

Full Citation in the ACM Digital Library

SESSION: Keynotes

Minecraft as AI Playground and Laboratory

Modern video games provide exciting challenges and opportunities for pushing the state of the art in machine learning and other research areas, and, in turn, stand to first benefit from research advances. For driving research, games provide rich data that can be used to tackle hard problems, from complex decision making to collaboration. If and when these are successfully tackled, new algorithms and insights have the potential to enable entirely new game experiences.

This talk focuses on opportunities in the setting of the game Minecraft, one of the most popular video games of all time. Minecraft is an open-world game, where players explore, create, and continuously find new ways to play and engage with each other. This open-ended nature both make the game appealing to its human fan-base, and uniquely challenging to AI algorithms. To unlock the potential of Minecraft for AI experimentation, my team has developed Project Malmo -- an open source experimentation platform built on top of Minecraft to enable a wide range of research. Here, I will illustrate the capabilities of the platform with recent examples that I find particularly exciting.

I will highlight our most recent collaboration, led by a team of PhD students at Carnegie Mellon University: the MineRL competition. This ambitious competition is designed to drive advances in sample efficient reinforcement learning with human priors. Sample efficient learning is a key challenge, with current algorithms often requiring millions of samples to learn to perform individual narrow tasks, limiting the scope and applicability of these approaches. This competition is built around a complex task, large-scale demonstration data, and an evaluation setup that requires and rewards sample efficient learning and effective generalization.

Looking out into the future, I will conclude by highlight selected open questions and challenges that have high potential for impact in video games and raise key questions for current state-of-the-art AI approaches.

The Creativity Process behind GRIS

GRIS is the journey of a girl dealing with the most painful experience in her life. Explaining this story with no words or dialogue has been a great challenge for Nomada Studio. Adrian Cuevas will explain the process of creation for GRIS, showing the different tools, references and ideas that were used during the production of the game. Art, Music, Animation, Game Design, ... everything is extremely important to have a consistent narrative and engage the player with a story that will not be told. On top of that GRIS targets all kind of audience, even people that are not used to play video games. This will brought more challenges to the design and construction of the game. Adrian will talk about some of the decisions that were made to make the game more appealing to non-gamers.

SESSION: Paper Session 1: emBodied Gaming

Astaire: A Collaborative Mixed Reality Dance Game for Collocated Players

Despite the growth of Virtual Reality (VR), the design space of collocated social play in VR remains narrow. Here we present Astaire, a collaborative hybrid VR dance game for two players sharing an HTC Vive VR system. The game resulted from a design research process using embodied design methods, and drawing upon concepts in HCI and Play Design, including social affordances, and asymmetric and interdependent play. Here we present insights from a study playtesting Astaire alongside two VR games that inspired ours: Keep Talking and Nobody Explodes (KTNE), and Audioshield. We examined players' and spectators' enjoyment, and interpersonal relationships, which were self-reported higher for Astaire. Using data from semi-structured interviews, we foreground design elements that impacted our participants' play experience, grouped under the themes of balance of players' roles, the physicality afforded by the game, and the social experience enabled. Our work contributes to opening the design space of hybrid collocated VR--through our game, we surface inspirational design concepts in HCI, and share design knowledge gained during our design process.

Movement Empowerment in a Multiplayer Mixed-Reality Trampoline Game

Insufficient physical activity motivation is a major public health problem. Exergames-games requiring physical exertion-can be designed to support motivation. For example, granting superhuman movement abilities to players has been shown to support one's feeling of competence, an innate human need and a core intrinsic motivation factor posited by self-determination theory. In this paper, we present Super Stomp, a multiplayer mixed-reality trampoline game that empowers movement by exaggerating jump height both in the real world and in the game. We contribute a novel dual-trampoline game system and game mechanics for implementing engaging multiplayer gameplay. This provides an exemplar of satisfying the challenging constraints that real-world movement empowerment technology can impose on exergame movement safety and feasibility. We further contribute insights into the effect of empowering movement on need satisfaction through an in-the-wild study involving 26 participants who played Super Stomp at an indoor activity park.

iGYM: An Interactive Floor Projection System for Inclusive Exergame Environments

In traditional sport settings, players with mobility disabilities typically do not have opportunities to engage in physical play with their peers without mobility aids and vice versa. In this paper, we present an interactive floor projection system, iGYM, designed to enable people with mobility disabilities to compete on par with, and in the same physical environment as, their peers without disabilities. At the core of iGYM are the concept of peripersonal circle interaction and adjustable game mechanics, which enable individualized game calibration and wheelchair-accessible manipulation of virtual targets on the floor. Based on a pilot study, we determined three adaptation levels designed to make the system (I) accessible, (II) more playable, and (III) more balanced. We conducted a user study with 12 children testing the effects of these levels. Findings indicate that higher adaptation levels were not always preferred. Player preferences were multifactorial and also based on their desire to challenge themselves. Perceptions of fairness were often formed regardless of whether players used wheelchairs or not.

Towards Age-friendly Exergame Design: The Role of Familiarity

Exergames have been shown to be effective in helping older adults maintain their physical abilities. However, it is sometimes difficult for older adults to experiment with exergames due to a perceived digital divide. In this work, we propose to bridge this divide through infusing familiarity design into exergames. Specifically, we identify five sub-constructs of familiarity, namely prior experience, positive emotion, occurrence frequency, level of processing, and retention rate. We evaluate the correlations between these five sub-constructs and familiarity through a field study involving 59 Singaporean older adults. Four exergames designed with different interfaces and tasks were sequentially played by the participants. Questionnaire and interview data about the participants' assessment of the five sub-constructs and the overall familiarity on different exergames were collected. The analysis results show that all five sub-constructs have significant positive correlations with familiarity. Moreover, there is a high positive correlation between the participants' perceived familiarity of the exergame and their satisfaction with the exergame. Informed by these results, we propose familiarity design guidelines based on the five sub-constructs for age-friendly exergames.

Fiddling, Pointing, Hovering, and Sliding: Embodied Actions with Three Evaluation Tools for Children

In user studies with children, it is important to use age appropriate evaluation tools to better understand their preferences, opinions, and thoughts. Here, we studied two accepted evaluation tools: The Five Degrees of Happiness, and the Sticky Ladder rating scale; together with the Paper Ladder, a paper version of the latter. Thirty-six preschoolers rated two creative and play activities ("Painting" and "Construction Blocks") and a game ("Musical Chairs") in terms of difficulty, enjoyment, and preference. Drawing from theories of embodied and distributed cognition, we performed a video analysis of the children's interactions with these tools, focusing on how each tool supported the children's cognitive processes and communication with the researcher. Here, we first describe children's embodied behavior and discuss how these were supported by design features and affordances of the tools. Then, we discuss strengths and shortcomings of each evaluation method. Last, we provide recommendations for their design, appropriation, and usage by researchers developing and evaluating playful solutions and games for children.

Turning Your Book into a Game: Improving Motivation through Tangible Interaction and Diegetic Feedback in an AR Mathematics Game for Children

Augmented reality game-based learning has become an emerging trend in the field of education as it has the potential to increase children's learning motivation for subjects such as mathematics. However, to achieve the benefits for children effectively, AR serious games need to be appropriately designed, especially in respect to their novel interactions and representation paradigms. In this paper, we report on an exploratory experiment to investigate how different interaction techniques (digital screen-touch interaction vs real-world tangible interaction) and different feedback mechanisms (non-diegetic feedback vs diegetic feedback) affect 7-8-year-old children's motivation for mathematics learning. Our results show that diegetic feedback led to the game being considered significantly more enjoyable, as well as inducing greater feelings of competence and autonomy; screen-touch interaction versus tangible interaction did not change motivation directly, nor did we find interaction effects between the presentation and interaction modes. By analyzing the results and based on previous studies, we identify recommendations for designers to develop motivating serious AR games for children.

SESSION: Paper Session 2: Streaming and the Crowd

Game or Live Streaming?: Motivation and Social Experience in Live Mobile Quiz Shows

Live quiz shows that make use of mobile applications embed aspects of both games and live streaming. To understand users' motivations and experiences related to these mobile quiz shows, we used a mixed-methods approach that includes interviews (N = 16) and a survey (N = 296). We conducted a thematic analysis of interviews to identify seven motivations, five of which were verified through a factor analysis of survey data: interactivity, offline integration, achievement, ease of enjoyment, and financial incentives. Moreover, we examined how those motivations influenced users' perceptions of the apps and their in-app behavior patterns. The motivations of offline integration and financial incentives positively affected users' frequency of app usage, their recommendation of the app, and their habitual usage. This result implies that, to drive persistent usage, it is important to foster social integration and to properly balance both the average chance of winning and the amount of distributed prize money. Furthermore, our results suggest new directions for using design implications to improve user engagement.

Understanding Digital Patronage: Why Do People Subscribe to Streamers on Twitch?

Digital patronage is the act of delivering recurring direct support to content creators online. In this paper, we define digital patronage and examine why patrons engage in this behavior on the live streaming platform Twitch. Our mixed method research illustrates patrons' motivations, how patronage motivations differ from that of donations, and the motivational factors that are associated with higher levels of patronage. We discuss how results extend understanding of patronage in the context of social support theory and provide design implications for digital patronage platforms.

Toward a Twitch Research Toolkit: A Systematic Review of Approaches to Research on Game Streaming

The rise of game streaming services has driven a complementary increase in research on such platforms. As this new area takes shape, there is a need to understand the approaches being used in the space, and how common practices can be shared and replicated between researchers with different disciplinary backgrounds. In this paper, we describe a formal literature review of game streaming research. Papers were coded for their research focus, primary method, and type of data collected. Across the prior work we found three common themes: (1) work that is readily supported by existing technical infrastructure, (2) work that does not require explicit technical support, (3) and work that would benefit from further technical development. By identifying these needs in the literature, we take the first step toward developing a research toolkit for game streaming platforms that can unify the breadth of methods being applied in the space.

ARAPID: Towards Integrating Crowdsourced Playtesting into the Game Development Environment

Iterative playtesting of games is crucial, but remains a time consuming and ad-hoc process. In this work, we streamlined and systematized the playtesting process by adding support for crowdsourced, on-demand playtesting directly into a game development environment to test and evaluate platform games. Our system, called ARAPID (As Rapid As Possible Iterative Design), manages playtesting from a control panel in Unity and recruits players from Mechanical Turk. With this system, game designers can launch playtests and visualize results directly in the editor. To better understand and evaluate this approach, we ran three studies on two basic platform games. First, a game designer used ARAPID to playtest and rapidly iterate on the design of the games; we found the games were improved toward specific design goals. Second, we analyzed the impact of different forms of recruitment on playtesting speed; we found that pre-recruitment and over-recruitment of players can reduce the time needed to run playtests. Third, we analyzed the impact of players' familiarity with the game on the precision of playtest results; we found that whether or not players are allowed to replay the game can impact results.

Designing Videogames to Crowdsource Accelerometer Data Annotation for Activity Recognition Research

Human activity recognition using wearable accelerometers can enable in-situ detection of physical activities to support novel human-computer interfaces and interventions. However, developing valid algorithms that use accelerometer data to detect everyday activities often requires large amounts of training datasets, precisely labeled with the start and end times of the activities of interest. Acquiring annotated data is challenging and time-consuming. Applied games, such as human computation games (HCGs) have been used to annotate images, sounds, and videos to support advances in machine learning using the collective effort of "non-expert game players." However, their potential to annotate accelerometer data has not been formally explored. In this paper, we present two proof-of-concept, web-based HCGs aimed at enabling game players to annotate accelerometer data. Using results from pilot studies with Amazon Mechanical Turk players, we discuss key challenges, opportunities, and, more generally, the potential of using applied videogames for annotating raw accelerometer data to support activity recognition research.

Crowdjump: Investigating a Player-Driven Platform Game

We present Crowdjump, a player-driven online platform game: players could post ideas on how to improve the game, the platform, or any related aspect. Continuously, all players could then choose ideas which were implemented and released on a daily basis. We conducted an exploratory study with 25 players over the course of 23 days and aimed at releasing two features per day. We analyzed idea types and could show that players did not change an idea voting scheme based on up- and down-votes and were more focused on changing the game than any other component. In contrast, features that would improve the community feeling or would help to improve ideas of others were not often suggested or selected. Nonetheless, the experience was rated as quite enjoyable by players, showing the appeal of such a player-driven game design approach and the relevancy for further research in this context.

SESSION: Paper Session 3: Dissecting the Player Experience

Power-Ups in Digital Games: The Rewarding Effect of Phantom Game Elements on Player Experience

Power-ups are a type of game reward that allow the player to customise their experience by altering gameplay for a short period of time. Despite the wide use of power-ups in video games, little is known about their effect on gaming experiences. To explore this, we conducted an experimental study that compares the experiences of players depending on their exposure to power-ups in a recreational video game. The results show that players who collected power-ups felt significantly more immersed in the game, experienced more autonomy, but did not feel more competent or challenged than those who played the game without these collectables. Interestingly, a similar effect was observed for those players who picked up 'placebo' power-ups, despite the items having no effect on the gameplay. We provide a discussion of these results and their implications both for games user researchers and game designers.

Press Pause when you Play: Comparing Spaced Practice Intervals for Skill Development in Games

Games allow players to fulfill the need for competence by providing well-designed, increasingly difficult challenges. To meet these challenges, players repeatedly attempt to achieve objectives---and through this repetition, they improve their game skills. Players are keenly aware of whether they are making progress during these attempts, and they want to get better as quickly as possible. Previous research suggests that one way of improving skill development is by taking breaks between periods of activity (called "spaced practice''). However, there is little knowledge about whether this idea works in games, what the optimal break length is, and whether the effects last. We carried out a study comparing spaced and continuous practice in a Super Hexagon clone, using five-minute play intervals and five break lengths (no break, two minutes, five minutes, ten minutes, one day). We found that spaced practice led to significant gains in performance, particularly for novices. This result shows that players can achieve an immediate improvement in skill development, simply by scheduling short breaks in their play session; designers can also make use of this result by building rest periods into the structure of their games. Our study also indicated that breaks are valuable both in the short and the longer term---in a retention test after one day, all of the groups performed similarly, suggesting that even if a player does not use spaced practice initially, taking a break after the play session can still lead to improvements. Our study provides new information that can aid in the design of practice schedules for perceptual-motor tasks in games.

Juicy Game Design: Understanding the Impact of Visual Embellishments on Player Experience

Visual embellishments (VEs) are design elements that support information already conveyed by other means. In games, this concept is known as juiciness, and refers to the provision of redundant feedback in situations where a single player action triggers multiple non-functional reactions. Academia and industry both view the concept as a means of improving player experience; however, empirical evidence to back the assumption is lacking. Here, we present findings from two studies: one initial study with 40 participants comparing the effects of visual embellishments in two research games, the Frogger-clone Cuber, and the FPS game Dungeon Descent, and a second study with 32 participants using the commercially available game Quake 3 Arena. Results show that visual embellishments contribute to the visual appeal of all games, but only affects aspects such as competence under specific circumstances. We discuss implications of our findings for the integration of visual embellishments and juiciness, and their relevance for game development.

Notification in VR: The Effect of Notification Placement, Task and Environment

Virtual reality (VR) is commonly used for entertainment applications but is also increasingly employed for a large number of use cases such as digital prototyping or training workers. Here, VR is key to present an immersive secondary world. VR enables experiences that are close to reality, regardless of time and place. However, highly immersive VR can result in missing digital information from the real world, such as important notifications. For efficient notification presentation in VR, it is necessary to understand how notifications should be integrated in VR without breaking the immersion. Thus, we conducted a study with 24 participants to investigate notification placement in VR while playing games, learning, and solving problems. We compared placing notifications using a Head-Up Display, On-Body, Floating, and In-Situ in open, semi-open, and closed VR environments. We found significant effects of notification placement and task on how notifications are perceived in VR. Insights from our study inform the design of VR applications that support digital notifications.

Effects of Background Music on Risk-Taking and General Player Experience

Music affects our emotions and behaviour in real life, yet despite its prevalence in games, we have a limited understanding of its potential as a tool to explicitly influence player experience and behaviour in games. In this work, we investigate whether we can affect players' risk-taking behaviour through the presence and attributes of background music. We built a game that operationalizes risk behaviour by repeatedly giving players the choice between a safe but less rewarding course, and a risky but potentially more rewarding course. In a mixed-design user study (N=60), we explored the impact of music presence, tempo, and affective inflection on players' in-game risk behaviour and overall player experience. We found an effect of music presence on risk behaviour in the first playthrough, i.e., in the absence of other prior knowledge about the game. Further, music affect and tempo affected player immersion, as well as experienced mastery and challenge. Based on these findings, we discuss implications for game design and future research directions.

SESSION: Paper Session 4: Gustatory and Other Sensations

Playful Human-Food Interaction Research: State of the Art and Future Directions

In response to calls for sense-making in the field of Human-Food Interaction, we offer a systematic review of a subset of HFI works that we call Playful HFI-interventions that use game- or play-inspired mechanisms to add value to food-related experiences. To support our review, we offer a conceptual model of Playful HFI informed by: (i) the 34 publications in our dataset; (ii) theories of play, games and HFI; and (iii) previous reviews of play-related HCI. Our conceptual model and review characterise the current state of Playful HFI, highlight resemblances and differences with the broader field of HFI as a whole and surface challenges and opportunities in this new and exciting design space. Our contribution will help HFI scholars to explore new and increasingly playful avenues for the future of food technology and will empower the HFI community to better position (and critically reflect on) future research at the intersection of play, technology and food.

Towards Understanding the Design of Playful Gustosonic Experiences with Ice Cream

There is an increasing trend that explores the convergence of digital play and eating to support a playful relationship with food. We note that interactive sound, although prevalent in digital game design, has only received limited attention in this trend. To contribute to an understanding of "playful gustosonic experiences", we present a design and study of a novel capacitive-sensing ice cream cone, "iScream!". In a study with 32 participants, the cone played four different sounds (a roaring, crunchy, giggling, and burping sound in order to explore fantasy facilitation, food congruency, anthropomorphism and bodily response) when eating ice cream. The results are two themes derived from six findings each, which detail how players explored the different auditory interaction possibilities with their eating actions while the sounds in turn modified those eating actions. Based on these findings, we present four design tactics for designers aiming to create playful gustosonic experiences to ultimately facilitate a more playful relationship with food.

Unpacking the Audio Game Experience: Lessons Learned from Game Veterans

People with or without visual impairments play and enjoy audio games. While this genre of computer games has attracted a strong fan base and some attention in HCI, little research has been dedicated to the people who actually play audio games in their daily life. There is a pressing need to capture the viewpoints of authentic or expert players, designers and developers to advance audio game design. Thus, we give voice to seven game veterans of sound-based gaming, i.e., people who each have more than a decade of profound experience in playing or designing audio games. We conducted a total of 14 interviews and employed grounded theory methods to unpack their experiences. We found that audio games enriched their life through creativity, play, and social exchange. Those core concepts were influenced by peripheral concepts like, inter alia, aesthetics & enjoyability, accessibility, or the availability of audio games. We show how they relate to each other and discuss design implications.

Interactive Soft Toys for Infants and Toddlers - Design Recommendations for Age-appropriate Play

Very young children (below three) are characterized by sensory-motor exploration and pre-cognitive development. There is little work on interactive toys for this age group. This raises the question of what interactions are developmentally appropriate at this age. We here propose recommendations for designing meaningful interactive toys, gained from designing an interactive soft (textile) book prototype, testing it with children and discussion of observations with parents, as well as three expert interviews. Recommendations concern what types of interactions to implement (transparent and one-step), inviting full-body activity and exploration with all senses, what kind of effects to generate (appropriate for children's abilities, being predictable, with clear relation to real-world experiences, but also accounting for the needs of caregivers), and the importance of allowing for shared experience.

An Analysis of Longitudinal Trends in Consumer Thoughts on Presence and Simulator Sickness in VR Games

Since the release of the Oculus Rift CV1 in 2016, millions of VR headsets have found their way into consumer homes. In this paper, we sought to understand what shifts have taken place within the two years since consumer VR became available. In this paper, we consider what can be learned about long-term use of consumer VR through an analysis of discussions in online forums devoted to VR. We gathered posts made on the /r/Vive subreddit from the first two years after the HTC Vive's release. We present the results from an in-depth qualitative analysis concerning immersion, presence, and simulator sickness. Over time, as users moved from passive to active, their attitudes and expectations towards immersion and simulator sickness matured. Major trends of interest found were game design implementation and locomotion techniques.

Outstanding: A Multi-Perspective Travel Approach for Virtual Reality Games

In virtual reality games, players dive into fictional environments and can experience a compelling and immersive world. State-of-the-art VR systems allow for natural and intuitive navigation through physical walking. However, the tracking space is still limited, and viable alternatives \commor extensions are required to reach further virtual destinations. Our work focuses on the exploration of vast open worlds -- an area where existing local navigation approaches such as the arc-based teleport are not ideally suited and world-in-miniature techniques potentially reduce presence. We present a novel alternative for open environments: Our idea is to equip players with the ability to switch from first-person to a third-person bird's eye perspective on demand. From above, players can command their avatar and initiate travels over large distance. Our evaluation reveals a significant increase in spatial orientation while avoiding cybersickness and preserving presence, enjoyment, and competence. We summarize our findings in a set of comprehensive design guidelines to help developers integrate our technique.

SESSION: Paper Session 5: Emotions, Traits and Player Experiences

Recognizing Emotional Expression in Game Streams

Gameplay is often an emotionally charged activity, in particular when streaming in front of a live audience. From a games user research perspective, it would be beneficial to automatically detect and recognize players' and streamers' emotional expression, as this data can be used for identifying gameplay highlights, computing emotion metrics or to select parts of the videos for further analysis, e.g., through assisted recall. We contribute the first automatic game stream emotion annotation system that combines neural network analysis of facial expressions, video transcript sentiment, voice emotion, and low-level audio features (pitch, loudness). Using human-annotated emotional expression data as the ground truth, we reach accuracies of up to 70.7%, on par with the inter-rater agreement of the human annotators. In detecting the 5 most intense events of each video, we reach a higher accuracy of 80.4%. Our system is particularly accurate in detecting clearly positive emotions like amusement and excitement, but more limited with subtle emotions like puzzlement.

Exploring Emotional Attachment to Game Characters

Engaging game characters are often key to a positive and emotionally rich player experience. However, current research treats character attachment in a rather generic manner with little regard for the differing emotional qualities that may characterize this attachment. To address this gap we conducted a qualitative online survey with 213 players about the game characters they are particularly fond of. We identify seven distinct forms of emotional attachment, ranging from feeling excited about the characters' gameplay competency, admiring them as role models, to deep concern for characters' well-being. Our findings highlight the emotional range that players experience towards game characters, as well as provide implications for the research and design of emotional character experience in games.

"Horror, guilt and shame" -- Uncomfortable Experiences in Digital Games

Gameplay frequently involves a combination of positive and negative emotions, where there is increasing interest in how to design for more complex forms of player experience. However, despite the risk that some of these experiences may be uncomfortable, there has been little empirical investigation into how discomfort manifests during play and its impact on engagement. We conducted a qualitative investigation using an online survey (N=95), that focused on uncomfortable interactions across three games: Darkest Dungeon, Fallout 4 and Papers, Please. The findings suggest games create discomfort in a variety of ways; through providing high-pressure environments with uncertain outcomes and difficult decisions to make, to the experience of loss and exposing players to disturbing themes. However, while excessive discomfort can jeopardize player engagement, the findings also indicate that discomfort can provide another facet to gameplay, leading to richer forms of experience and stimulating wider reflections on societal issues and concerns.

"One of the baddies all along": Moments that Challenge a Player's Perspective

Reflection has become a core interest for game designers. However, empirical research into the kinds and causes for reflection within games is scarce. We therefore conducted an online questionnaire where participants (n=101) openly reported perspective-challenging moments within games, their causes, experience, and impact. Where past work has emphasized transformative reflection that changes player's views and behavior outside the game, we found that players report predominantly moments of 'endo'-transformative reflection, which is focused on players' game-related behavior and concepts. We further identify some causes of perspective-challenging moments relating to narrative, game systems, game-external sources, and player expectations. Narrative reveals emerge as a key cause of perspective challenge.

The Role of Uncertainty in Moment-to-Moment Player Motivation: A Grounded Theory

Uncertainty is widely acknowledged as an engaging characteristic of games. Practice and research have proposed various types and factors of game uncertainty, yet there is little work explaining when and why different kinds of uncertainty motivate, especially with respect to 'micro-level', moment-to-moment gameplay. We therefore conducted a qualitative interview study of players tracing links between uncertainty experiences, specific game features, and player motives. Data supports that uncertainty is indeed a key element in keeping players motivated moment-to-moment. We present a grounded theory of seven types of engaging gameplay uncertainty emerging from three sources - game, player, and outcome - and document links to likely underlying motives, chief among them curiosity and competence. Comparing our empirically grounded taxonomy with existing ones shows partial fits as well as identifies novel uncertainty types insufficiently captured in previous models.

Player Characteristics and Video Game Preferences

The Games User Research literature has advanced considerably on understanding why people play games and what different types of games or mechanics they prefer. However, what has been less studied is how models of player preferences explain their game choices. In this study, we address this question by combining and analyzing two datasets (N = 188 and N = 332) containing data about the games that participants enjoy, their player trait scores, and their preferred game elements and playing styles. The results provide evidence that these scores can significantly explain participants' preferences for different games. Additionally, we provide information about the characteristics of players who enjoy each game.

SESSION: Paper Session 6: Broader Reflections

Ethereum Crypto-Games: Mechanics, Prevalence, and Gambling Similarities

Ethereum crypto-games are a booming and relatively unexplored area of the games industry. While there is no consensus definition yet, 'crypto-games' commonly denotes games that store tokens, e.g. in-game items, on a distributed ledger atop a cryptocurrency network. This enables the trading of game items for cryptocurrency, which can then be exchanged for regular currency. Together with their chance-based mechanics, this makes crypto-games part of the recent convergence of digital gaming and gambling. In a first effort to scope the field, this paper surveys popular crypto-games, which use the Ethereum cryptocurrency, to tease out characteristic technical properties and gameplay. It then compares the games' features with criteria found in current legal and psychological definitions of gambling. We find that the popular crypto-games selected meet a combined legal and psychological definition of gambling, and conclude with ramifications for future research.

Who Purchases and Why?: Explaining Motivations for In-game Purchasing in the Online Survival Game Fortnite

As a popular and free-to-play multiplayer online survival game, Fortnite not only offers novel game mechanics but also allows players to purchase special in-game items using real money. Based on an online survey of 215 Fortnite players, this paper investigates in-game behaviors that can be used to explain who is more likely to spend money in Fortnite. Specifically, players' motivations to spend real-life money were categorized; how the amount of spending was correlated with different motivations and behavioral factors was also analyzed. In contrast to prior virtual goods literature that associates in-game purchasing with social and task motivations, we found that motivations to make in-game purchases in Fortnite were less about assimilating with others and more about looking visually unique from others. We conclude by discussing how the survival genre of battle royale and other game affordances may explain these findings.

The Surrogate Body in Play

Games research within the Human-Computer Interaction (HCI) community currently draws most of its understanding of immersion, engagement and player experience from Psychology. However, these phenomena are also studied by the humanities, i.e., Media Theory, a field that conceptualises these parameters as affective and situated in specific contexts. Here, we draw from surrogate body (Leihkörper) theory proposed by Voss for cinematic experiences, and apply it to a variety of different contexts in which digital games are played. Doing so, we not only refine the theory but also introduce a socio-technical, cultural and affective understanding of play contexts that can contribute to how we examine players' experiences. Further, we provide a case detailing how Games Research can engage with humanistic theories, and explore their relevance for the design and evaluation of digital games.

Hacking Masculine Cultures - Career Ambitions of Female Young Professionals in a Video Game Company

Women employed in video game companies are facing several barriers regarding equality and career chances. Scholars argue that career development of women is at times hindered because of hegemonic masculinity in organizations, with networks and other social factors playing a more important role than qualifications. This means that women miss out on career opportunities in a thriving and future driving industry. Yet, as gendered working environments are considered to be the result of social construction, they can also be restructured. To explore the drivers of these aspects, we conducted a qualitative field study in a video game company in a large city in Germany to understand what challenges regarding masculinity exist and how they are dealt with. Our lessons learned contribute to the realization of more gender-sensitive working environments in the video game sector and, as a result, of more diverse video games as well. Furthermore, a native English speaker dealt with typos and linguistic infelicities.

Peer Feedback Processes in the Game Industry

A wide variety of design strategies, tools, and processes are used across the game industry. Prior work has shown that these processes are often collaborative, with experts in different domains contributing to different parts of the whole. However, the ways in which these professionals give and receive peer feedback have not yet been studied in depth. In this paper we present results from interviews with industry professionals at two game studios, describing the ways they give feedback. We propose a new, six step process that describes the full feedback cycle from making plans to receive feedback to reflecting and acting upon that feedback. This process serves as a starting point for researchers studying peer feedback in games, and allows for comparison of processes across different types of studios. It will also help studios formalize their understanding of their own processes and consider alternative processes that might better fit their needs.

SESSION: Paper Session 7: Beyond the Stereotypical

Beyond Human: Animals as an Escape from Stereotype Avatars in Virtual Reality Games

Virtual reality setups are particularly suited to create a tight bond between players and their avatars up to a degree where we start perceiving the virtual representation as our own body. We hypothesize that such an illusion of virtual body ownership (IVBO) has a particularly high, yet overlooked potential for nonhumanoid avatars. To validate our claim, we use the example of three very different creatures---a scorpion, a rhino, and a bird---to explore possible avatar controls and game mechanics based on specific animal abilities. A quantitative evaluation underpins the high game enjoyment arising from embodying such nonhuman morphologies, including additional body parts and obtaining respective superhuman skills, which allows us to derive a set of novel design implications. Furthermore, the experiment reveals a correlation between IVBO and game enjoyment, which is a further indication that nonhumanoid creatures offer a meaningful design space for VR games worth further investigation.

The Role of Assertiveness in a Storytelling Game with Persuasive Robotic Non-Player Characters

Can social agents be assertive and persuade users? To what extent do the persuasion abilities of robots depend on the users' own traits? In this paper, we describe the results of a study in which participants interacted with robotic Non-Player Characters (NPC) displaying different levels of assertiveness (high and low), in a storytelling scenario. We sought to understand how the level of assertiveness displayed by the robots impacted the participants' decision-making process and game experience. Our results suggest that NPCs displaying lower levels of assertiveness evoke more positive emotional responses but are not more effective at influencing players' decisions when compared to NPCs displaying higher levels of this trait. However, NPCs displaying a personality trait are more effective persuaders than NPCs not displaying this feature. Overall, this paper highlights the importance of considering the player's personality and its relation to task-specific attributes during the process of game design.

Cross-Car, Multiplayer Games for Semi-Autonomous Driving

We investigate and characterize a design space for in-car games based on a survey of previous work, and identify an opportunity for "cross-car" multiplayer games played among occupants in nearby cars. This is supported by innovations in automotive technology like autonomous driving, full-window heads-up displays, and ad hoc communication between vehicles. In a custom virtual reality driving simulator, we created three games to illustrate design dimensions: Killerball, a competitive free-for-all game; Billiards, a player versus player, massively multiplayer online game with player assists; and Decoration, an idle-style game with multiplayer resource management. A 12-participant evaluation with a semi-structured interview revealed a positive response to input controls and HUDs, and suggests game genres have a similar effect on time for an emergency driving takeover task. We used insights from our process and evaluation to formulate design considerations for future cross-car games.

Not Just for Girls: Encouraging Cross-Gender Role Play and Reducing Gender Stereotypes with a Strategy Game

Harsher socio-cultural sanctions against cross-gender role play amongst boys versus girls create comparatively greater pressure for boys to adhere to traditional gender roles [29]. At the same time, strategically orchestrated play experiences may offer a potential means of counteracting this pressure. In the present research, a pair of randomized experiments, involving a strategy game that puts players in the role of princesses, revealed a positive impact of delaying the timing of the revelation of the characters' gender (Study 1) and reducing the degree of femininity of the illustrated representation of the characters (Study 2) on boys' evaluations of the game, level of experience-taking (identification and role assumption) with the princess characters, and shift in both gender perceptions and self-perceptions. Together, these findings illustrate that strategic design choices can facilitate boys' adoption of cross-gender personae and open the door to malleability in adherence to rigid gender roles and norms.

"It Started as a Joke": On the Design of Idle Games

With idle games, active withdrawal from the game comprises an essential part of gameplay as players wait for the game state to change over time. This mode of interaction is paradigmatic for the change of roles technologies have in our lives. However, the design elements of idle games are less well understood, particularly from the perspectives of developers. We interviewed six designers of six different popular idle games and inquired into their individual approaches. Via thematic analysis, we refine and expand on existing definitions of idle games as a genre, shed light on ethically charged practices of care in their design, and identify shared core characteristics between the games and processes. We then generate intermediate-level knowledge on the design of idle games. Our work contributes designers' perspectives on idle games and their design to a growing body of literature on the genre.

Germ Destroyer - A Gamified System to Increase the Hand Washing Duration in Shared Bathrooms

Washing hands is important for public health as it prevents spreading germs to other people. One of the most important factors in cleaning hands is the hand washing duration. However, people mostly do not wash their hands for a long enough time leading to infections and diseases for themselves and others. To counter this, we present "Germ Destroyer", a system consisting of a sensing device which can be mounted on the water tap and a mobile application providing gameful feedback to encourage users to meet the recommended duration. In the mobile application, users kill germs and collect points by washing their hands. Through a laboratory study (N=14) and a 10-day in-the-wild study (363 hand washing sessions), we found that Germ Destroyer enhances the enjoyment of hand washing, reduces the perceived hand washing duration, almost doubles the actual hand washing duration, and has the potential to reduce the risk of infection.

SESSION: Paper Session 8: Design

A Canvas for Participation-Centered Game Design

The Game Design activity is often conditioned by pre-existing assumptions of what constitutes a game and its constituting elements, which can lead to repetitive designs and all too familiar experiences. In trying to support the education of a new generation of designers so as to leave the comfort zone of familiar objects, we proposed a design canvas with six perspectives for which to conceptualize player participation in the experience. For each perspective, we proposed a set of questions designed to prompt new lines of thought regarding design intent, game object, and player participation. The canvases were tested throughout three research iterations and improved based on qualitative evaluations of their influence in game design learning processes. The canvas was generally found to be effective at quickly pulling inexperienced game design participants to consider a variety of innovative play experiences, beyond what we would expect from derivative design from examples.

A Framework for Motivating Sketching Practice with Sketch-based Gameplay

Sketching is a valuable skill to learn but requires extensive motivation and practice to improve. We present a framework for motivating practice with sketch-based gameplay that is rooted in a grounded theory study of the motivations of various individuals with different skills levels. The individuals interviewed included a range from novice and intermediate industrial design students to established design professionals. Four categories emerged that explain the differences in motivation between individuals with different skill levels, including achievement, competition, communication, and creativity. We also present a case study of the implementation of two different gameplay approaches for encouraging line work practice in a high school art course and a university sketching course. The study revealed that both approaches were very engaging and motivating to students, with 72,842 lines practiced across the 150 students overall. We also gained insights about how the approaches differed in motivating students, and share principles we learned on motivating students with gameplay that may be useful to other researchers, educators, and technologists.

Incremental Game Mechanics Applied to Text Annotation

We argue that the mechanics of 'Ville type Free-To-Play (F2P) games in general, and incremental games in particular, is especially suited for Games-With-A-Purpose. We demonstrate this through WordClicker, an incremental game whose mechanics is designed for text labelling. We believe the design and mechanics used are highly transferable to other games featuring annotation where game design is a challenge, such as serious games and language resourcing GWAPs. The game was tested with audiences from three popular indie gaming portals, achieving promising results both for entertainment value and learning.

Factors to Consider for Tailored Gamification

Gamification is widely used to foster user motivation. Recent studies show that users can be more or less receptive to different game elements, based on their personality or player profile. Consequently, recent work on tailored gamification tries to identify links between user types and motivating game elements. However findings are very heterogeneous due to different contexts, different typologies to characterize users, and different implementations of game elements. Our work seeks to obtain more generalizable findings in order to identify the main factors that will support design choices when tailoring gamification to users' profiles and provide designers with concrete recommendations for designing tailored gamification systems. For this purpose, we ran a crowdsourced study with 300 participants to identify the motivational impact of game elements. Our study differs from previous work in three ways: first, it is independent from a specific user activity and domain; second, it considers three user typologies; and third, it clearly distinguishes motivational strategies and their implementation using multiple different game elements. Our results reveal that (1) different implementations of a same motivational strategy have different impacts on motivation, (2) dominant user type is not sufficient to differentiate users according to their preferences for game elements, (3) Hexad is the most appropriate user typology for tailored gamification and (4) the motivational impact of certain game elements varies with the user activity or the domain of gamified systems.

Game Dynamics that Support Snacking, not Feasting

Player experience research tends to focus on immersive games that draw us into a single play session for hours; however, for casual games played on mobile devices, a pattern of brief daily interaction---called snacking ---may be most profitable for companies and most enjoyable for players. To inform the design of snacking games, we conducted a content analysis of game mechanics in successful commercial casual games known to foster this pattern. We identified five single-player game dynamics: Instant Rewards, Novelty, Mission Completion, Waiting, and Blocking. After situating them in theories of motivation, we developed a game in which game mechanics that foster each dynamic can be included individually, and conducted two studies to establish their relative efficacy in fostering the behavioural pattern of snacking, finding significant potential in Novelty and Waiting. Our work informs the design of games in which regular and brief interaction is desired.

Representation and Frequency of Player Choice in Player-Oriented Dynamic Difficulty Adjustment Systems

Dynamic difficulty adjustment (DDA) systems can improve the player experience (PX). Allowing the player to make difficulty adjustment decisions can lead to an improved sense of control. However, we hypothesize that shifting the responsibility for making difficulty adjustment decisions from the computational system to the player may be detrimental to the overall PX. We conducted a controlled experiment, analyzing data from 84 participants, to investigate how (1) the way difficulty choices are presented (integrated into game mechanics or direct control) and (2) the frequency of presenting these choices to the player (once, periodically, or constantly) affects the PX. Our findings show that integrated choices lead to an improved PX along some PX dimensions. Presenting choices once or constantly yields poorer PX compared to presenting choices periodically. The results also demonstrate interaction effects between the two experiment factors, suggesting the need for more deliberate design decisions when designing for difficulty adjustment.

SESSION: Paper Session 9: Analyzing and Visualizing Player Behavior

Modeling Individual and Team Behavior through Spatio-temporal Analysis

Modeling players' behaviors in games has gained increased momentum in the past few years. This area of research has wide applications, including modeling learners and understanding player strategies, to mention a few. In this paper, we present a new methodology, called Interactive Behavior Analytics (IBA), comprised of two visualization systems, a labeling mechanism, and abstraction algorithms that use Dynamic Time Wrapping and clustering algorithms. The methodology is packaged in a seamless interface to facilitate knowledge discovery from game data. We demonstrate the use of this methodology with data from two multiplayer team-based games: BoomTown, a game developed by Gallup, and DotA 2. The results of this work show the effectiveness of this method in modeling, and developing human-interpretable models of team and individual behavior.

User Guided Movement Analysis in Games using Semantic Trajectories

Understanding how players navigate through virtual worlds can offer useful guidance for map and level design of video games. One way to handle large-scale movement data obtained within games is by modelling movement as a sequence of visited locations instead of focusing on raw trajectory data. In this paper, we introduce a visualization approach for movement analysis based on semantic trajectories derived from a user-guided segmentation of the game environment. Based on this concept, the visualization offers an aggregated view of movement patterns together with the possibility to view individual paths for detailed inspection. We report on a user study with six experts from the game industry and compare the insights they have gleaned from the visualization with feedback from players. Our results indicate that the approach is successful in localizing problematic areas and that semantic trajectories can be a valuable addition to existing approaches for player movement analysis.

Looking Outside the Box: Reflecting on Gaze Interaction in Gameplay

Gaze interaction in games moved from being a tool for accessibility to be at the core of mass-market game franchises, offering enhanced controller performance and greater immersion. We propose to explore three different popular gaze-based interaction mechanics to create novel opportunities in the game design space. We developed Twileyed, a collection of three games that challenge the "common" use of gaze as a pointer to navigate; select; and aim; to pose a challenging new way to play with the eyes. We used the games as data to reflect on the gaze design space. We asked users to play the games to validate them, and we observed their experience and strategies. Based on the observations, we discussed through 5 themes, the dimensions of gaze interactions and the potential outcomes to create engaging and playful gaze-enabled games. We contribute a position in gaze gameplay design, but also a conversation starter to engage the EyePlay research community.

Assessing the Impact of Visual Design on the Interpretation of Aggregated Playtesting Data Visualization

Making effective use of data generated from players interacting with games (often via playtesting to improve game quality) is a challenging task since the datasets are often mixed and very large. To address this, various visualization techniques have been introduced to help game developers cope with the data. However, there is a gap in research concerning the impact of different visual designs on the interpretation of gameplay data. In this paper, we propose four alternative visual designs of an aggregated visualization and assess how professional game developers interpret the data differently due to the changes in the visual designs. Our results provide an understanding and a supporting argument about the impact of the visual properties transparency and shading (both positive and negative) on the interpretation of the represented data. This is an important contribution to the field of Games User Research given the current move towards data-informed decision making and the popularity of data visualizations.

Age? It's in the Game: An Exploratory Study on Detection of Cognitive Aging through Card Games

We report on an exploratory study for assessing cognitive aging based on the acquisition and modeling of player data of commercial off-the-shelf games. To this end, candidates for digital biomarkers of cognitive performance were captured via FreeCell, from three distinctive age groups (18-25, 40-55, 65+) from 52 participants, playing for a total of 130 game rounds. Next, features were engineered and a machine learning model (Logistic Regression) was trained. We found features retained for the model to support theories on fluid intelligence and cognitive functions sensitive to cognitive aging. Performance metrics suggest that our model is successful in classifying young and older participants. However, classifying middle-aged players remains problematic. To conclude, this study suggests that commercial off-the-shelf games hold promise for the acquisition of digital biomarkers on cognitive aging and provides benchmark data for future studies. Nevertheless, as this is a first, exploratory study, further research is necessary.