Post
A networking model where all clients run the same simulation in sync, exchanging only player inputs instead of world state.
Lockstep is the classic RTS networking model. Each client simulates the full game deterministically and exchanges only input commands. The advantage is stunning: you can have 8 players with thousands of units each on the same battlefield with tiny bandwidth requirements. The disadvantage is brutal: any desync — even a single floating-point mismatch — and the game is broken. It also means no player can take their turn before the slowest player's input arrives, capping tick rate to the slowest link.
Example
StarCraft and Age of Empires II used lockstep to run massive simultaneous battles over dialup. Factorio uses lockstep for its deterministic factory simulation. Most fighting games moved away from lockstep toward rollback specifically because lockstep locks you to the worst ping in the room.
Why it matters
Lockstep explains a lot of gaming history: why old RTS games felt laggy, why desyncs were common, and why the industry moved toward authoritative-server models. It is also why some modern genres (Factorio, some MOBAs) still use it where determinism matters more than latency.
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