As one of the most disruptive human-computer interaction techniques, Virtual Reality (VR) provides a novel way to examine human movements, e.g. when investigating Body Ownership (BO) in the field of cognitive sciences, especially when the visual output diverges from real-world actions. Previous research in BO uses questionnaires and brain imaging, where the former is a highly subjective metric, and the latter is very costly in time, money, and personnel. To answer the question How can a VR serious game help overcome current challenges of BO assessment?, we designed Astral Body, a VR game that helps cognitive science researchers assess people’s level of BO. In the game, players are asked to grab ‘flying collectibles’ coming from a portal in space. Researchers can inject different types and levels of asynchrony into the arms of the visualized avatar, thus affecting the players’ BO experience and perception. Players, in turn, can also report whenever they perceive possible mismatched avatar behavior. In addition, researchers can analyze player data, including looking for unconscious responses, e.g. small adjustments in physical movements to mitigate injected asynchrony. Preliminary results from playtesting and qualitative analysis of Astral Bodyindicate that a VR game can effectively help researchers investigate BO phenomena.

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Procedural Content Generation (PCG) has long been proposed as an answer to the increased workload imposed on designers of virtual worlds, although often at the cost of controllability and expression of designer intent. Mixed-initiative approaches promise to overcome this, and valid proposals have been made of mixed-initiative editors, e.g. driven by the Wave Function Collapse (WFC) algorithm [12]. However, stock WFC operates on a simple tileset without any hierarchy or semantic clustering, preventing designers from fluently expressing level of detail, leaving the constraint solving burden partly on them instead of on the algorithm. Hierarchical Semantic Wave Function Collapse (HSWFC) claims to solve this problem by hierarchically structuring its tileset of semantic tiles, featuring meta-tiles that can undergo intermediate collapses [2]. Employing an HSWFC interactive editor offering such features may significantly reduce cognitive load and, thus, make such an editor more appealing for widespread use. We describe a user study to test this hypothesis, by comparing and discussing the cognitive load assessed on designers using either a stock WFC-driven editor or an HSWFC-driven editor. Our findings confirm that there is a significant reduction in cognitive load when the HSWFC editor is employed in comparison to the stock WFC editor.@en

A narrative world typically consists of several interrelated locations that, all together, fully support enacting a given story. For this, each location in a narrative world features all the objects as required there by the narrative, as well as a variety of other objects that plausibly describe or decorate the location. Procedural generation of narrative worlds poses many challenges, including that, First, it cannot lean only on domain knowledge (e.g., patterns of objects commonly found in typical locations), and, second, it involves a temporal dimension, which introduces dynamic fluctuations of objects between locations. In this article, we present a novel approach for the procedural generation of narrative worlds, following two stages: first, a narrative world mold is generated (only once) for a given story; second, the narrative world mold is used to create one (or more) possible narrative worlds for that story. For each story, its narrative world mold integrates spatio-temporal descriptions of its locations with the object semantics and the domain knowledge previously acquired on typical locations. We describe how a narrative world mold can be generated, as well as how it can be fed to existing procedural generation methods, to create a variety of narrative worlds that fit that narrative. We evaluate our own implementation of this approach, performing a number of experiments that illustrate both the expressive power of narrative world molds and their ability to steer the generation of narrative worlds.

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Conventional gait rehabilitation methods have the risk of alienating the patient due to their monotonous nature, thus negatively impacting the effectiveness of gait training. Modern technologies can help provide patients with better support, safety and immersive experience during training. However, physiotherapists cannot be required to master those technologies, nor to spend much time designing a more varied and engaging treatment for each patient. In this paper, we argue that adaptive gamified gait rehabilitation based on procedural content generation (PCG) can effectively support physiotherapists in achieving such customized outcomes. We propose a generic adaptation scheme to steer the generation of movement challenge levels based on player modeling and therapists' intervention. Our approach features two difficulty adjustment strategies: parameter progression schemes and integration of multiple therapy goals. These strategies are applicable to the personalization of a wide range of gait rehabilitation goals. We implemented this approach in a standalone prototype for supporting gait training with the RYSEN system, a three-dimensional overground body weight support system. From our assessment with physiotherapists, we conclude that our PCG-based adaptive method effectively assists therapists in (i) offering a broad diversity in gait exercises to a wide group of patients, and (ii) dynamically tailoring challenge levels for a variety of gait tasks.

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There are few proposals to improve the interactivity and control of wave function collapse (WFC) in a mixed-initiative setting. Moreover, most WFC algorithm variants operate on an simple, unstructured set of tiles. This limitation on the level of control provided to designers hampers their creative work in various ways. We propose Hierarchical Semantic WFC, a generalized approach to WFC that organizes its tile-set into a hierarchy akin to a taxonomy induced by the relation 'consists-of'. In such a hierarchical structure, abstract tiles (i.e. non-leaf nodes) can represent the first sketchy intentions of a designer (e.g. forest, urban, desert,...) This allows a designer to interactively collapse a given area into abstract tiles, while subsequently, (and repeatedly, if desired) WFC can resolve each area into a variety of particular instances, by further collapsing it into (a valid combination of) its children tiles (whether leaves or not). We identify how this subtle tile-set change affects the whole WFC algorithm, describe a number of novel exploratory and interactive functions that this enables, and showcase these with a variety of examples generated with our prototype implementation. We conclude that these new mixed-initiative content generation methods can considerably reduce design iteration times and improve the assistance given to designers in expressing their creative intent.

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Mostly, restorative environments, like parks and forests, are only thought of in the real world. However, one can wonder whether their restorative effects translate to a virtual world; and whether the environment itself makes any difference. In order to assess the possible translation of restorative properties from the real world to a virtual setting, we developed Resto Quest, a single-player, first-person exploration game, designed to investigate the possible restorative effects of both natural and urban virtual environments. Resto Quest is playable on a normal personal computer, and its main game play loop consists of exploring the environment, locating in it a task to accomplish, and completing a simple minigame. After completion of each minigame, a positive change in the scenery takes place. Evaluation of Resto Quest has shown that players found its game mechanics relaxing, and that the minigames offer balanced difficulty between two interchangeable environments.

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Most storytelling games bring people together to co-create stories. However, they often require considerable creative effort and skills from all players, possibly discouraging less resourceful participants and impairing stories' quality. Moreover, most stories created within these games are usually only kept in players' minds rather than on storage, despite being a valuable and original asset, with a large potential for the narrative research community. We address these challenges with a novel mixed-initiative approach aimed at supporting a group of players to incrementally co-create a story, one sentence at a time. Our method features a hand generator that offers a unique set of tokens (words) to each player in each turn. This generator carefully combines tokens relevant to the ongoing story, to each individual player, to the group as a whole and random. We implemented this method in TaleMaker, a multiplayer online game that stimulates playful co-creation of a story. TaleMaker gives players considerable creative freedom to compose their sentences, combining a gentle structural steering with the wisdom of the group to determine the best direction for the story. The collected output of TaleMaker consists of annotated stories, with slots (e.g. action, character, location) filled with words associated with a WordNet synset. From a preliminary evaluation, players reported that TaleMaker effectively stimulated story authoring, and perceived TaleMaker-created stories of considerable quality. In addition, a first analysis of the collected tokens confirms that players mostly collected story-related tokens, rather than those randomly offered.

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In recent years, the use of Augmented and Virtual Reality (ARNR) has taken a larger role within training and education of various fields, but not every individual experiences the benefits that AR and VR technology are thought to provide. The perspective taking skill of an individual may be a good indicator of the effectiveness that AR and VR training can achieve. However, we found that the tests in other research targeting small scale perspective taking are few and limited, as perspective taking is often hard to distinguish from mental rotation. Therefore, we designed and developed A Hole New Perspective, a serious game created specifically to test and train an individual’s perspective-taking ability. A Hole New Perspective focuses on the relationship between a 3D object floating in the air and a 2D hole on a moving wall. The core game mechanics consists of having the player rotate the object so that it fits in the hole, before the wall hits the object. Because players do not always have an aligned view with the hole, they have to call on their spatial perspective-taking abilities, in addition to mental rotation. We tested the game with a variety of test subjects, and compared these test results with the Perspective Taking/Spatial orientation Test. Early results have shown that performance in the game corresponds to mental rotation ability. Furthermore, there are indications that improvement in spatial ability through the game is selectively present for those with lower spatial abilities. This further substantiates the need for a more individualized approach when offering AR and VR in education. Additional training may be needed for some, but not all students.@en

Wave Function Collapse (WFC) is a powerful generative algorithm, able to create locally-similar output based on a single example input. One of the inherent limitations of the original WFC is that it often requires users to understand its inner workings, and possibly make their own ad-hoc mods, to achieve satisfactory results. Besides distracting from your creative task, this strongly reduces the algorithm's effective usefulness to a small group of technical users. We propose miWFC, a novel mixed-initiative approach to WFC aimed at overcoming these drawbacks. Its main focus is on providing intuitive control to its users, in a way that matches their usual creative workflow. Among its main features, this approach provides (i) interactive navigation through design history, including controlled backtracking, (ii) precise manual editing of the output for direct expression of design intent, and (iii) interactive manipulation of tile weights, to tweak the global appearance of the output. We evaluated a prototype implementation of our approach among game artists and other creative professionals, and concluded that its features were largely considered useful and supportive of their creative work.

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Several datasets of stories and text have been proven useful for a variety of research fields. Yet, many of these datasets have suffered from the burden of being manually authored and/or annotated, affecting their size and potential to grow. To overcome this problem, we propose a novel database of stories collected from TaleMaker, an online multiplayer game that facilitates the playful co-creation of a story in order to eliminate the tedious task of authoring and annotating a dataset of stories. TaleMaker's database relational schema provides a simple story representation, in which stories are named and clearly annotated. A story is composed of a sequence of plot points, each with several slots (e.g. action, character, location) filled with sense-annotated tokens (words) associated with a WordNet synset. In this paper, we describe in detail the database schema of TaleMaker's stories repository. In addition, we suggest some of the potential applications of this repository of stories, including fostering research in fields such as story generation, narrative world generation, and word sense disambiguation.

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Many people think of reforestation projects as one-dimensional, simply consisting of planting trees. In reality, a reforestation project takes into account a wide variety of factors, of which the three most important are improving soil quality, reducing fire hazard, and ensuring the prosperity of the community. We posit that a simplistic view on such projects is detrimental for a more committed and serious societal awareness and support of sustainable reforestation. Therefore, it is desirable that more people have a better understanding of the interplay of these factors, as they will likely become more involved in reforestation projects. We present Benni’s Forest, a serious game aimed at increasing awareness of the challenges of reforestation projects. Benni’s Forest is a simulation game, in which the player is responsible for a reforestation project, balancing its various factors over the years, deciding on what to do when and where on the terrain, e.g. fertilizing, planting trees, or digging fire ditches. Meanwhile, adverse events, like wildfires or illegal logging, threaten your progress, creating a tension that gives the player a vivid experience of the complexity of the project. As you progress, several scores indicate the quality of your performance, most notably a biodiversity score, representing the amount and variety of trees in the forest. In this way, players receive clear hints to strategize and face each situation with the appropriate measures to grow a biodiverse forest. We evaluated Benni’s Forest conducting a survey amongst players. The results confirm both an increased understanding of the challenges involved in reforestation efforts, and an increased sense of engagement of players with such projects.@en

Mathematics education plays an essential role in children’s development, and there are many online applications aimed at supporting this process. However, manually creating math problems with a variety of textual and visual content is very time-consuming and expensive. This article presents a generic approach for procedural generation of mathematical problems, including their corresponding textual representations. The content generation process consists of two phases: Abstract math problem generation and text generation. For the generation of abstract math problems, we propose a generic template-based method that operates across a variety of difficulty-levels and domains, including arithmetic, comparison, ordering, mathematical relationships, measurement, and geometry. Subsequently, we propose a multi-language adaptive textual content generation pipeline to realize the generated abstract math problems into semantically coherent text questions in natural language. A workflow time gain evaluation shows that the system yields an average time saving of 56%. Further, human expert evaluation of this approach indicates that the content it generates is sensible and solvable for primary school students.

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Presently, one of the greatest challenges of humankind is climate change. It is usually assumed that its mitigation will require an extensive adaptation in many human habits. As every fourth ton of carbon dioxide emitted can be attributed to the food chain, it is argued that one of the most effective actions an individual can take is changing towards a more sustainable diet, like a plant-based one. Serious games have proved to be a successful means for achieving behavior change. We present Veganity, your journey, a mobile serious game aimed at assisting players in their transition towards a more plantbased diet. The game combines the characteristics of the idle game genre with diet tracking: in the game, as you progress in adapting your personal diet, you spare energy that can be spent in making the game world more sustainable. Personal factors, like changing your ecological or social norms, your habits and your behavioral costs and benefits, are targeted by different game mechanics. These include, among others, a currency mechanism for stimulating habit change, in-game actions building up selfefficacy, and tips raising problem awareness. Besides describing our game design, we also present the main features of the game implementation. From a preliminary evaluation, we conclude that Veganity, your journey successfully engages players in pursuing their own diet goals, and increases their reflection on, and acquaintance with, sustainable diet behaviors. @en

Sport games are among the oldest and best established genres of computer games. Sport-inspired environments, such as RoboCup, have been used for AI benchmarking for years. We argue that, in spite of the rise of increasingly more sophisticated game genres, team sport games will remain an important testbed for AI benchmarking due to two primary factors. First, there are several genre-specific challenges for AI systems that are neither present nor emphasized in other types of games, such as team AI and frequent replanning. Second, there are unmistakable nonskill-related goals of AI systems, contributing to player enjoyment, that are most easily observed and addressed within a context of a team sport, such as showing creative and emotional traits. We analyze these factors in detail and outline promising directions for future research for game AI benchmarking, within a team sport context.

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A narrative world (NW) is an environment which supports enacting a given story. Manually creating virtual NWs (e.g. for games and films) requires considerable creative and technical skills, in addition to a deep understanding of the story in question. Procedural generation methods, in turn, generally lack in creativity and have a hard time coping with the numerous degrees of freedom left open by a story. In contrast, mixed-initiative approaches offer a promising path to solve this tension. We propose a mixed-initiative approach assisting an NW designer in choosing plausible entities for the locations, where the story takes place. Our approach is based on a recommender method that uses common and novel associations to narrative locations, actions and entities. Our method builds upon a large dataset of co-occurrences of disambiguated terms that we retrieved from photo captions. Building on this knowledge, our solution deploys entity (un)relatedness, offers clusters of semantically and contextually related entities, and highlights novelty of recommended content, thus effectively supporting the designer’s creative task, while helping to stay consistent with the story. We demonstrate our method via an interactive prototype called roleTaleForge. Designers can obtain meaningful entity suggestions for their NWs, which enables guided exploration, while preserving creative freedom. We present an example of the interactive workflow of our method, and illustrate its usefulness.

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Most content creation applications currently in use are conventional PC tools with visualisation on a 2D screen and indirect interaction, e.g. through mouse and keyboard. Augmented Reality (AR) is a medium that can provide actual 3D visualisation and more hands-on interaction for these purposes. This paper explores how AR can be used for story authoring, a peculiar type of content creation, and investigates how both types of existing AR interfaces, tangible and touch-less, can be combined in a useful way in that context. The Story ARtist application was developed to evaluate the designed interactions and AR visualisation for story authoring. It features a tabletop environment to dynamically visualise the story authoring elements, augmented by the 3D space that AR provides. Story authoring is kept simple, with a plot point structure focused on core story elements like actions, characters and objects. A user study was done with the concept application to evaluate the integration of AR interaction and visualisation for story authoring. The results indicate that an AR interface combining tangible and touch-less interactions is feasible and advantageous, and show that AR has considerable potential for story authoring. @en

Within citizenship education, a new focus is being laid upon what is expected of citizens within a diverse and lightning-fast society: more emphasis is placed on teaching students how to understand and respect other people’s opinions, regardless of how they may contrast with one’s own. However, learning to be tolerant with others’ viewpoints comes with hurdles, as currently it is quite easy to become stuck within one’s own worldview. We developed Diermocratie, an in-classroom game aimed at encouraging a more open conversation, which breaks through these hurdles and addresses key competencies such as empathy and argumentation. By role-playing metaphors that parallel real-world events, students explore their own predispositions, are made aware of the perspectives of others, and are enabled to discuss issues objectively. From a preliminary evaluation, most students could identify the parallelism between the in-game metaphor and real-world situations. They also indicated that the game motivates them to further talk to each other, approaching sensitive topics among them.

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Most content creation applications currently in use are conventional PC applications with visualisation on a 2D screen and indirect interaction, e.g. through mouse and keyboard. Augmented Reality (AR) is a medium that can provide actual 3D visualisation and more hands-on interaction for these applications, due to its technology adding virtual elements to a real-world environment. We explored how AR can be used for story authoring, a specific type of content creation, and investigated how both types of existing AR interfaces, tangible and touch-less, can be combined in a useful way in that context [1]. The Story ARtist application was developed to evaluate the designed interactions and AR visualisation for story authoring. It features a tabletop environment to dynamically visualise the story authoring elements, augmented by the 3D space that AR provides. Story authoring is kept simple, with a linear plot point structure focused on core story elements like actions, characters and objects.

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Procedural content generation (PCG) for architecture is widely used in a variety of digital media, most notably in games. However, such methods are often limited in their expressive range, and require considerable technical knowledge to create non-trivial architectural structures. We present a novel tile-based PCG approach for generating architecture, that proposes the use of architectural profiles, a declarative characterization of architectural typology, within a generic tile solving framework. An architectural profile consists of a set of tiles, representing atomic architectural building blocks, and a set of declarative constraints and rules, specifying which conditions a tile configuration has to satisfy to be valid. These conditions are translated into logic constraints, and used by a tile solver to control tile placement in a bottom-up manner. Eventually, each valid model output by the solver is a representative instance of its architectural profile. We describe an implementation of this approach with Answer Set Programming, using an off-the-shelf constraint solver for model generation. We performed an expressive range analysis, and concluded that our declarative method is quite controllable and can be steered over a broad range of architectural structures, regarding density and repetitiveness. Due to this expressive range and control, our tile-based method is very suitable for the customized development of urban environments for games.

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