How do you design a record replay system for a frequently changing game? I'm working in a free MMORPG and I have a problem. I'm (with other people) developing a video recording system for the game. The idea is basically we record all the packages sent amp received with timestamps, plus some local data from the client, and then dump it in a file. For playing the video, we just emulate everything that's on the file. We also have an option to export the video to avi with ffmpeg. The problem is when we change between versions of the game, it is hard to maintain backwards compatibility for the video (commands added removed, function changes, etc). Is there a good way to handle this problem? instead of having a bunch of different players and choose the right one for each version of the video file? It would be helpful to know how does other games handle this situation. Thanks for the help, sorry for my english.