One of the most dicult tasks when creating an online multiplayer game is to provide the players with a consistent view of the virtual world despite the network delays. Most current games use prediction algorithms to achieve this, but usually it does not go beyond applying the DIS [2] dead reckoning algorithm proposed in the mid-90s. In this paper we introduce a simulator called GLS that allows us to evaluate dierent aspects of DIS and its variations. We examine the impact of prediction and clock synchronization on game consistency. We also evaluate the convergence algorithm we introduce here. Furthermore we look into ways for compensating increasing delays to keep the player's view of the game state suciently consistent with other players.

Multiplayer online games are becoming increasingly popular as broadband internet connections replace the old modems. However, while available bandwidth grows steadily according to Moore's law, the latency of the internet connections remains almost constant, making it dicult to maintain a consistent game state over a large number of clients that have to be synchronized with each other and with the server(s). This paper introduces a possible solution to the problem by dening the necessary level of consistency through user's perception of the game. While the resulting set of requirements is somewhat dicult to formalize, it is not too restrictive and leaves many options open, some of which are discussed here. Ideally a game where all the requirements are met will appear like a local game to the user.

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