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.

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Network lag is a fact of life for networked games. Lag can cause game states to diverge at different nodes in the network, making it difficult to maintain the illusion of a single shared space. Traditional lag compensation techniques help reduce inconsistency in networked games; however, these techniques do not address what to do when states actually have diverged. Traditional consistency maintenance (CM) does not specify how to make gamecritical decisions when players' views of the shared state are different, nor does it indicate how to repair inconsistencies. These two issues -decision-making and error repair -can have substantial effects on players' gaming experience. To address this shortcoming, we have characterized a range of algorithmic choices for decisionmaking and error repair. We report on a study confirming that these algorithms can have significant effects on player experience and performance, and showing that they are often more important than degree of consistency itself.

Lag compensation algorithms used in networked games require programmers to manage the complexities of dealing with both time and shared state. This can make implementing lag compensation techniques challenging. The difficulties in expressing these algorithms limit experimentation with different algorithms and inhibit programmers from exploring the space of the algorithms and testing their effects. The solution is to have a programming model that is better able to deal with time. In this paper, we present such a programming model, timelines. Timelines dramatically reduce the time and effort required to implement lag compensation techniques by allowing for the explicit treatment of time. The timelines model has been implemented as part of the Janus toolkit.

Abstract. For expert interfaces, it is not obvious whether providing multiple modes of interaction, each tuned to different sub-tasks, leads to a better user experience than providing a more limited set. In this paper, we investigate this question in the context of air traffic control. We present and analyze an augmented flight strip board offering several forms of interaction, including touch, digital pen and physical paper objects. We explore the technical challenges of adding finger detection to such a flight strip board and evaluate how expert air traffic controllers interact with the resulting system. We find that users are able to quickly adapt to the wide range of offered modalities. Users were not overburden by the choice of different modalities, and did not find it difficult to determine the appropriate modality to use for each interaction.