SpacetimeDB is a transactional, relational, multiplayer database that eliminates the need for separate game servers. Developers write modules in Rust or C# that run directly within the database, handling all game logic and persistent state. This serverless architecture simplifies deployment and scales efficiently, as demonstrated by its use in the BitCraft MMORPG. SpacetimeDB offers ACID properties, real-time queries, and features like time travel debugging and user-generated logic. Backed by significant investment, it promises high performance and ease of use for building massive multiplayer games.