game-development-unity-unity-multiplayer-engineer

Client-side prediction applies player input locally for immediate responsiveness while sending the same input to the server via ServerRpc. The server simulates authoritative movement into a NetworkVariable, and the client reconciles by snapping back when the predicted position diverges beyond a threshold.

Use NetworkVariable for persistent state that must sync to all clients on join, such as health or score. Use RPCs for one-time events: ServerRpc for client input requests and ClientRpc for server-confirmed events like hit effects.

Yes, Unity Relay supports player-hosted games by routing traffic through Relay servers, which also hides host IP addresses. The host creates an allocation and shares a join code that clients use to connect through JoinAllocationAsync.

Keep the server authoritative over all game-state truth and validate every ServerRpc input server-side, such as checking movement against velocity caps. Clients should send inputs only, never position or damage values, and rate limiting can detect impossible RPC frequencies.

NetworkVariable change events fire on every value change, so setting values every frame in Update() generates constant traffic. Throttle non-critical updates to around 10Hz, use dirty checks, and prefer NetworkTransform or custom prediction for position sync.