Cheating in on-line games is a prevalent problem for both game makers and players. The popular real-time strategy game genre is especially vulnerable to cheats, as it is frequently hosted as a peer-to-peer game. As the genre has moved towards a distributed simulation approach to gameplay, the number of cheats has been reduced to bug exploits and “maphacks”: a form of information exposure that reveals the opponent’s units and positions when they should be hidden. This paper proposes a technique for detecting maphacking based on bit commitment and explores the tradeoffs in network traffic and information exposure inherent in reducing information exposure in peer-to-peer games. Categories and Subject Descriptors C.2.4 [Distributed Systems]: Distributed Applications General Terms Algorithms, Performance, Security Keywords cheating,games,peer-to-peer