MultiGen: Level-Design for Editable Multiplayer Worlds in Diffusion Game Engines
This work addresses the lack of user control and shared inference in video world models, enabling editable and multiplayer experiences for game developers and interactive simulation users.
MultiGen introduces an explicit external memory into diffusion game engines, enabling editable, persistent world states and real-time multiplayer interactions with coherent cross-player consistency.
Video world models have shown immense promise for interactive simulation and entertainment, but current systems still struggle with two important aspects of interactivity: user control over the environment for reproducible, editable experiences, and shared inference where players hold influence over a common world. To address these limitations, we introduce an explicit external memory into the system, a persistent state operating independent of the model's context window, that is continually updated by user actions and queried throughout the generation roll-out. Unlike conventional diffusion game engines that operate as next-frame predictors, our approach decomposes generation into Memory, Observation, and Dynamics modules. This design gives users direct, editable control over environment structure via an editable memory representation, and it naturally extends to real-time multiplayer rollouts with coherent viewpoints and consistent cross-player interactions.