Mauve wrote some interesting articles [1] back in 2012 on the roll-back principle being used in GGPO, which is a (semi) popular netcode used for fighting games.

Mauve wrote some interesting articles [1] back in 2012 on the roll-back principle being used in GGPO, which is a (semi) popular netcode used for fighting games. In the likely event that you don't play fighting games, I'll break down briefly the needs of the genre. Fighting games are almost always animated at 60 frames per second. Different moves will come out in a certain number of frames, be active for a certain number of frames, and have recovery animation for a certain number of frames. When you have all of that information for a character, it's called (unsurprisingly) "frame data". Let's say you and your opponent are standing right next to each other. You press light punch, and he presses heavy punch, and it turns out that he was just a little faster and pressed his punch button a tenth of a second before you did; that's six frames. HOWEVER, his heavy punch is a really slow button; it has ten frames of startup animation before the punch even comes out! Your light punch is much faster; it comes out in only 3 frames. So he hits punch, six frames pass, and then you press punch as well. Three more frames pass, and your punch is active, but he's still in the startup animation. So even though he hit a button well before you did, you're actually hitting him first. There's a lot more to the strategy (if your punch hits him, he's going to go into some kind of hit animation; how long does that last? If you can get another attack to come out and hit him before that animation ends, then there's no way for him to block the second attack; this is the basis behind the concept of a combo in fighting games. Interestingly, it was initially a bug in Street Fighter 2.) but for the purposes of networking, all you need to understand is that frames are crucially important to a fighting game, there need to be sixty of them a second, and delaying even one or two frames can make the different between counterhitting your opponent with a light, or getting counterhit yourself with a heavy. It's worth clicking around on a couple of Mauve's posts, because they tend to be pretty interesting. [1]: http://mauve.mizuumi.net/2012/07/05/understanding-fighting-game-networking/ http://mauve.mizuumi.net/2012/07/05/understanding-fighting-g...