deterministic multiplayer physics with rollback netcode

https://reddit.com/link/1rt4ouu/video/mlhitr2jmwog1/player

Server and clients run the same Rapier physics (shared Rust lib). The server only broadcasts inputs -- no position sync. Each client replays confirmed inputs on its own physics world and predicts ahead for the local player. When a correction arrives, it rewinds to the last confirmed snapshot and re-simulates forward. Positions are never sent over the wire, the same 6-byte input packets drive every object in the simulation