Netcode

When several people play online together, each of their devices is running its own copy of the game. Netcode is the umbrella term for the programming that keeps all those copies in agreement – sending inputs and positions between players, deciding what happened when two events clash, and hiding delay so the game still feels responsive.

Players usually talk about netcode when it is not working well: “the netcode is awful” means online matches feel laggy, inconsistent or unfair.

The basic problem

Information takes time to travel. If you fire at an opponent, by the time your shot reaches the server, they may already have moved. Netcode must decide whose view counts. Different games make different choices. Some trust the shooter’s view, which favours the attacker; some trust the server’s view; many use a combination with “lag compensation” that rewinds positions slightly to judge fairly. Each approach has trade-offs, which is why it is common to feel you were hit behind cover.

Common approaches

Many games use a central server that holds the official state of the match. Others connect players directly to each other, called peer-to-peer. Fighting games are known for two styles: delay-based netcode, which waits for the other player’s input before showing each frame, and rollback netcode, which predicts inputs and corrects mistakes afterwards. Related technical ideas include the server’s tick rate and interpolation, which smooths movement between updates.

What players can and cannot control

Netcode is decided by the developer, so players cannot change it directly. What you can control is your side of the connection: a stable, low-ping connection gives any netcode the best chance. If a game is widely criticised for its netcode, reviews and community discussions usually say so, which is worth checking before buying a game mainly for online play.