I'd LIKE to say Lady in the Water but no, the award goes to Legend of Chun-Li. Truly the worst videogame movie ever and yes I have seen nearly all of them including KOF and Tekken (both of which are FAR better than Legend of Chun-Li).
You see, the big difference between other videogame movies and Legend of Chun-Li is that STUFF HAPPENS IN OTHER MOVIES! Legend of Chun-Li was the most excruciatingly boring mess of NOTHING happening that I have ever seen!
The movie WANTS to better flesh out the backstory of Chun-Li in a realistic and mature way but it botches EVERYTHING right from the start SO BAD that you instantly stop caring. Nothing is even remotely accurate or canon and since these characters DO nothing either, why should we care? Now yes other videogame movies are horribly inaccurate but THEY don't dwell on their characters and try to half-assedly "flesh them out". No, they're too busy MAKING THINGS HAPPEN! Even the mind numbing self indulgent mess that was Lady in the Water had more...THINGS HAPPENING than this movie! As such Legend of Chun-Li isn't even So Bad It's Good the way KOF or House of the Dead is. No, it's just plain bad.