Adapt: Single to Multiplayer Expert guidance for retrofitting multiplayer into single-player games. NEVER Do (Expert Multiplayer Rules) Security & Authority - NEVER trust client-reported state — Clients own their 'Input', NOT their 'Position' or 'Health'. Server must validate every coordinate and health change. - NEVER use groups for authority checks — Use . Group registration is non-deterministic in high-latency joins. - NEVER allow unrestricted RPC rates — A malicious client can call a 'FireWeapon' RPC 10,000 times per second. Always implement rate-limiting ( ). Movement & Lag - NEVER skip…