The simulation loop
An authoritative server advances the world in fixed steps called ticks. A sixty four tick server simulates sixty four steps each second. On every tick the server gathers inputs that arrived, advances physics by a fixed delta, resolves collisions, and may broadcast a snapshot.
Fixed timestep matters
- A fixed delta makes the simulation deterministic and reproducible, which prediction and reconciliation depend on.
- Variable timesteps cause physics to behave differently under load, breaking client server agreement.
- If a tick runs long, the server accumulates the leftover time and may run extra catch up ticks.
Tick rate versus send rate
Tick rate is how often the world updates. Send rate is how often snapshots go out, often lower to save bandwidth. A high tick rate gives crisper hit detection but costs CPU, so the rate is a deliberate budget choice, not a free dial.
Key idea
A fixed tick rate gives a deterministic simulation heartbeat, separate from the send rate, balancing precision against CPU and bandwidth.