Rollback netcode

Rollback netcode is a way of handling online play that keeps the game responsive even when there is delay between players. Instead of waiting for an opponent’s input to arrive before moving on, the game predicts what they will do – usually that they will keep doing whatever they were doing – and carries on immediately. When the real input arrives, if the prediction was wrong, the game “rolls back” to the last correct moment, replays the corrected inputs and jumps to the present.

Rollback versus delay-based netcode

The older alternative, delay-based netcode, adds a short pause to every input so both players stay in step. With good connections this works, but as delay grows, the whole game feels sluggish and timing that players practised offline no longer works. Rollback keeps your own inputs instant at all times; the cost is that, when predictions fail, an opponent’s character may appear to jump slightly. With small delays these corrections are often invisible.

Where it came from

Rollback is closely associated with fighting games, where precise timing matters enormously. A key milestone was GGPO, middleware created by Tony Cannon, a co-founder of the fighting game community site Shoryuken, who released the first version in late 2006. GGPO predicted remote inputs and rolled back the game state when they turned out to differ. Its ideas have since influenced many fighting games and other genres, and players often check whether a new fighting game uses rollback before buying it.

What this means for you

If you play fighting games or other timing-heavy games online, rollback netcode generally gives a smoother experience. You still benefit from a good connection: rollback hides delay but does not remove it, and very high ping or packet loss will cause frequent, visible corrections. A wired connection remains the best upgrade.