Tadeusz Stach

Heuristic evaluation for games: usability principles for video game design

Most video games require constant interaction, so game designers must pay careful attention to usability issues. However, there are few formal methods for evaluating the usability of game interfaces. In this paper, we introduce a new set of heuristics that can be used to carry out usability inspections of video games. The heuristics were developed to help identify usability problems in both early and functional game prototypes. We developed the heuristics by analyzing PC game reviews from a popular gaming website, and the review set covered 108 different games and included 18 from each of 6 major game genres. We analyzed the reviews and identified twelve common classes of usability problems seen in games. We developed ten usability heuristics based on the problem categories, and they describe how common game usability problems can be avoided. A preliminary evaluation of the heuristics suggests that they help identify game-specific usability problems that can easily be overlooked otherwise.

Design of an exergaming station for children with cerebral palsy

We report on the design of a novel station supporting the play of exercise video games (exergames) by children with cerebral palsy (CP). The station combines a physical platform allowing children with CP to provide pedaling input into a game, a standard Xbox 360 controller, and algorithms for interpreting the cycling input to improve smoothness and accuracy of gameplay. The station was designed through an iterative and incremental participatory design process involving medical professionals, game designers, computer scientists, kinesiologists, physical therapists, and eight children with CP. It has been tested through observation of its use, through gathering opinions from the children, and through small experimental studies. With our initial design, only three of eight children were capable of playing a cycling-based game; with the final design, seven of eight could cycle effectively, and six reached energy expenditure levels recommended by the American College of Sports Medicine while pedaling unassisted.

Target assistance for subtly balancing competitive play

In games where skills such as targeting are critical to winning, it is difficult for players with different skill levels to have a competitive and engaging experience. Although several mechanisms for accommodating different skill levels have been proposed, traditional approaches can be too obvious and can change the nature of the game. For games involving aiming, we propose the use of target assistance techniques (such as area cursors, target gravity, and sticky targets) to accommodate skill imbalances. We compared three techniques in a study, and found that area cursors and target gravity significantly reduced score differential in a shooting-gallery game. Further, less skilled players reported having more fun when the techniques helped them be more competitive, and even after they learned assistance was given, felt that this form of balancing was good for group gameplay. Our results show that target assistance techniques can make target-based games more competitive for shared play.

Improving recognition and characterization in groupware with rich embodiments

Embodiments are visual representations of people in a groupware system. Embodiments convey awareness information such as presence, location, and movement -- but they provide far less information than what is available from a real body in a face-to-face setting. As a result, it is often difficult to recognize and characterize other people in a groupware system without extensive communication. To address this problem, information-rich embodiments use ideas from multivariate information visualization to maximize the amount of information that is represented about a person. To investigate the feasibility of rich embodiment and their effects on group interaction, we carried out three studies. The first shows that users are able to recall and interpret a large set of variables that are graphically encoded on an embodiment. The second and third studies demonstrated rich embodiments in two groupware systems -- a multiplayer game and a drawing application -- and showed that the enhanced representations do improve recognition and characterization, and that they can enrich interaction in a variety of ways.

Classifying input for active games

Active games are video games that involve physical activity. Active games capture input via a variety of devices such as accelerometers, cameras, pressure sensors and exercise equipment. Although active games have become highly popular, the interaction styles they support are poorly understood, and largely driven by the capabilities of individual hardware devices. In order to allow for a standard development approach, a better understanding of the interaction found in active games is required. We have investigated existing commercial and academic games in order to classify input for active games. Our classification abstracts input from hardware, providing a better understanding of the interaction itself. Our ultimate goal is to make it easier to develop active games independently of underlying input hardware.

TableTrays: Temporary, reconfigurable work surfaces for tabletop groupware

Most tabletop groupware systems provide a single shared display, and users must coordinate access to both resources and space. In many situations, it can be difficult to manage this shared space - for example, it can be difficult to deal with clutter, to partition the work area, to divide the task, and to work with multiple objects at a time. To address these limitations, we developed an interaction technique called TableTrays. It provides users with portable work surfaces that sit on the tabletop, and allows them to temporarily group sets of objects and organize the table area. TableTrays incorporates many of the capabilities that have been proposed for tabletop groupware into a single mechanism. In this paper we describe TableTrays and present the results of a study where six groups carried out a design task using the technique. The results suggest that they can help people manage space, objects, and collaboration in tabletop work.

Activate your GAIM: a toolkit for input in active games

Active games are video games that involve physical activity. Interaction in active games is captured via a variety of input devices such as accelerometers, cameras, pressure sensors and exercise equipment. It is difficult for programmers to deal with this profusion of devices, leading most active games to be tied to a particular hardware platform. In this paper, we introduce the GAIM toolkit. GAIM simplifies input handling in active games through a high-level API that abstracts the details of individual devices. This allows developers to write code independently of the input devices used, allows the toolkit to dynamically adapt to the devices a player has available, and allows people with different hardware to play together. We illustrate the approach through two active games developed using the GAIM toolkit.