Multiplayer state sync backend

Design the real-time multiplayer state-sync backend for a fast-paced online game: rooms of up to 64 players, each sending ~20 input updates/sec, where everyone must see a consistent, low-latency view of the shared world (player positions, projectiles) despite 50–150ms client RTTs and occasional packet loss. Requirements: cheating-resistant (a client can't teleport itself), the world stays consistent across players, and a single hot region shouldn't degrade. Walk through the architecture, the consistency model, and the network protocol choices.