Ricardo Lopes

Adaptivity Challenges in Games and Simulations: A Survey

In computer games and simulations, content is often rather static and rigid. As a result, its prescripted nature can lead to predictable and impersonal gameplay, while alienating unconventional players. Adaptivity in games has therefore been recently proposed to overcome these shortcomings and make games more challenging and appealing. In this paper, we survey present research on game adaptivity, identifying, and discussing the main challenges, and pointing out some of the most promising directions ahead. We first survey the purposes of adaptivity, as the principles that could steer an adaptation and generation engine. From this perspective, we proceed to thoroughly discuss adaptivitys targets and methods. Current advances and successes in this emerging field point to many yet unexplored research opportunities. Among them, we discuss the use of gameplay expectations, learning preferences, and assessment data in the integrated adaptation of game worlds, scenarios, and quests. We conclude that, among other methods, procedural content generation and semantic modeling can powerfully combine to create offline customized content and online adjustments to game worlds, scenarios, and quests. These and other promising methods, deserving ample research efforts, can therefore, be expected to significantly contribute towards making games and simulations even more unpredictable, effective, and fun.

Procedural Generation of Dungeons

The use of procedural content generation (PCG) techniques in game development has been mostly restricted to very specific types of game elements. PCG has seldom been deployed for generating entire game levels, a notable exception to this being dungeons: a specific type of game level often encountered in adventure and role playing games. Due to their peculiar combination of pace, gameplay, and game spaces, dungeon levels are among the most suited to showcase the benefits of PCG. This paper surveys research on procedural methods to generate dungeon game levels. We summarize common practices, discuss pros and cons of different approaches, and identify a few promising challenges ahead. In general, what current procedural dungeon generation methods are missing is not performance, but more powerful, accurate, and richer control over the generation process. Recent research results seem to indicate that gameplay-related criteria can provide this high-level control. However, this area is still in its infancy, and many research challenges still lie ahead, e.g., improving the intuitiveness and accessibility of such methods for designers. We also observe that more research is needed into generic mechanisms for automating the generation of the actual dungeon-geometric models. We conclude that the foundations for enabling gameplay-based control of dungeon-level generation are worth being researched, and that its promising results may be instrumental in bringing PCG into mainstream game development.

Generating Consistent Buildings: A Semantic Approach for Integrating Procedural Techniques

Computer games often take place in extensive virtual worlds, attractive for roaming and exploring. Unfortunately, current virtual cities can strongly hinder this kind of gameplay, since the buildings they feature typically have replicated interiors, or no interiors at all. Procedural content generation is becoming more established, with many techniques for automatically creating specific building elements. However, the integration of these techniques to form complete buildings is still largely unexplored, limiting their application to open game worlds. We propose a novel approach that integrates existing procedural techniques to generate such buildings. With minimal extensions, individual techniques can be coordinated to create buildings with consistently interrelated exteriors and interiors, as in the real world. Our solution offers a framework where various procedural techniques communicate with a moderator, which is responsible for negotiating the placement of building elements, making use of a library of semantic classes and constraints. We demonstrate the applicability of our approach by presenting several examples featuring the integration of a façade shape grammar, two different floor plan layout generation techniques, and furniture placement techniques. We conclude that this approach allows one to preserve the individual qualities of existing procedural techniques, while assisting the consistency maintenance of the generated buildings.

Constructive generation methods for dungeons and levels

This chapter addresses a specific type of game content, the dungeon, and a number of commonly used methods for generating such content. These methods are all “constructive”, meaning that they run in fixed (usually short) time, and do not evaluate their output in order to re-generate it. Most of these methods are also relatively simple to implement. And while dungeons, or dungeon-like environments, occur in a very large number of games, these methods can often be made to work for other types of content as well. We finish the chapter by talking about some constructive generation methods for Super Mario Bros. levels.

A semantic generation framework for enabling adaptive game worlds

Adaptive games are expected to improve on the pre-scripted and rigid nature of traditional games. Current research uses player and experience modeling techniques to successfully predict some game-play adjustments players desire. These are typically deployed to adapt AI behavior or to evolve content for simple game levels. In this paper we propose a generation framework aimed at creating personalized content for complex and immersive game worlds. This framework, currently under development, captures which content provided the context for a given personal gameplay experience. This model is then used to generate content for the next predicted experience, through retrieval and recombination of semantic gameplay descriptions, i.e. case-based mappings between content and player experience. Through its integration with existing player and experience modeling techniques, this framework aims at generating, in an emergent way, game worlds that better suit players. Dynamic game content, which responds to the player performance, has the ability to personalize player experience, potentially making games even more unpredictable and fun.

Using gameplay semantics to procedurally generate player-matching game worlds

The use of procedural content generation to support adaptive games is starting to gain momentum in current research. However, there are still many open issues to tackle, namely the reusability of methodologies. Our research focuses on reusable and generic methods for linking the procedural generation of 3D game worlds with gameplay, as measured by player modelling techniques. As the interface for that link, we propose the use of gameplay semantics, a knowledge representation technique that allows our case-based generator to match content to player models. We present and discuss the implementation of our proposed method in an existing game, Stunt Playground. Gameplay semantics is created by designers in a generic way and is then used to procedurally generate player-matching Stunt Playground game worlds, both at the design and game stage. Current results show that our approach can automatically create such adaptive game content, thus effectively bridging game world designers, procedural generation and gameplay.

Authoring adaptive game world generation

Current research on adaptive games has mainly focused on adjusting difficulty in a variety of ways, for example, by providing some control over adaptive game world generation. These methods, however, are mostly ad-hoc and require quite some technical skills. To the best of our knowledge, so far, there has been no adaptive method that is truly generic and explicitly designed to actively include game designers in the content creation loop. In this paper, we introduce a generic method that enables designers to author adaptivity of game world generation, in a very expressive and specific fashion. Our approach uses adaptation rules, which build atop gameplay semantics in order to steer the online generation of the game content. Designers create these rules by associating skill profiles, describing skill proficiency, with content descriptions, detailing the desired properties of the specific game world content. This game content is then generated online using a matching and retrieval approach. We performed user studies with both designers and players and concluded that adaptation rules provide game designers with a rich expressive range to effectively convey specific adaptive gameplay experiences to players.