Ricky “Infil” Pusch is a long-time fighting game fan and content creator. He wrote The Complete Killer Instinct Guide, an interactive and comprehensive website for learning about Killer Instinct. This article was originally published there.
At its core, netcode is simply a method for two or more computers, each trying to play the same game, to talk to each other over the Internet. While local play always ensures that all player inputs arrive and are processed at the same time, networks are constantly unstable in ways the game cannot control or predict. Information sent to your opponent may be delayed, arrive out of order, or become lost entirely depending on dozens of factors, including the physical distance to your opponent, if you’re on a WiFi connection, and whether your roommate is watching Netflix.
Online play in games is nothing new, but fighting games have their own set of unique challenges. They tend to involve direct connections to other players, unlike many other popular game genres, and low, consistent latency is extremely important because muscle memory and reactions are at the core of virtually every fighting game. As a result, two prominent strategies have emerged for playing fighting games online: delay-based netcode and rollback netcode.