Chess is an MMO now?

A developer built a massive multiplayer chess game with 1 million boards running on a single Go process. The system handles 150,000+ players making 15+ million moves using optimized protocols, rollback netcode, and smart data distribution. Key technical achievements include using Protocol Buffers for efficient serialization, implementing optimistic client updates with conflict resolution, and managing concurrent access with read/write mutexes. The architecture demonstrates how far you can scale with simple approaches like big arrays and mutexes, while highlighting the complexity of real-time multiplayer game state synchronization.