So far the best game to movie(by popular opinoin, not just mine) is the first Mortal Kombat movie. I actually used to be a pretty big MK fan so I know a bit about it. The second one was actually supposed to be good, they had a great script, good actors, big budget, all that good stuff. But the studio decided to cut the budget for some reason. Anyway they ended up taking out entire pieces of the plot, cutting characters, recasting for cheaper actors, rushing production, those kind of things. There was a sight I found serfing the web one time that had apparently gotten ahold of the leaked original version of the script, and listed all the changes that where made. It seems like it would have been good if they could have done what they wanted. However, the good news is that there is a third film in the making. New Line had a 10 year contract to make MK movies, but after they ruined the second movie the creators decided to wait for the contract to run up. It recently did and they are now with a new studio thats letting them do what they want. And the new movie is going to be the replacement for the second movie. They are going to pretend like the second movie never happened and just pick up right after the first one.
Also while talking about game movies, I absolutely love the Mario movie. It's so funny. My friends and me like to argue about the best/worst of whatever, like best song, worst movie, all that. We came to the conclusion that the Mario movie had the worst casting of all time. It was so funny. Someone said to themselves, "We need a giant turtle like dinosaur that spits fire, and fights plumbers. Who could we get? Wait, I know. Dennis Hopper!". Awesome.