Abstract : This thesis presents our work in computer science in human-computer interaction (HCI). The subject concerns the use of a new kind of computer called the interactive tabletop display. It is a table whose top is both a screen and a multi-touch detection device. Interactive tabletops open up new uses of computer applications by allowing several co-located users to work or play together on the same system. Tabletop's users naturally want to interact simultaneously on the shared surface. This simultaneity is difficult to observe in a collaborative and not artificial environment. Existing studies have not sufficiently analyzed the problems nor sought how the system can help manage concurrency.Our approach was to exploring simultaneous interactions by studying original situations where the system puts pressure on users. We explain how we used a video game as an exploration and experimentation tool. This thesis traces the design and development of RealTimeChess, a game for 2-4 players, a real-time version of Chess adapted to tabletops. We report the results of experiments on groups of 2 to 4 participants in situations of cooperation and competition, which helped to highlight problems and physical discomfort of access to remote objects, awareness in dynamic context, and control the pace of interaction.This thesis also presents lessons learned on simultaneous interactions of multiple users, territoriality aspects, collaborative behavior, and finally gives tabletop Game Design guidelines.