Most of them are complete crap really, but I loved Residen Evil (the first one) during that time I couldn't stop watching it, I got completely adicted to it!
I like first Mortal Combat, for me it is the only one good film based on game. AFAIK the first movie based on a game was Super Mario Bros.(it was in 1992 I think), however most of them IMO at least not good. And films directed by Uwe Boll below any level I could imagine, it's not even c-grade movies...
Well Resident Evil 1 and 2 was cool , Mortal Kombat and the Serrie too , All Uwe Bolls movies are crap (exept Alone in the Dark like this one ) wonders me if his next movies (Far cry and Dungeon Sige part 1 and part 2 ) will be any good , Double dragon was crap , ahmmmm Tron was cool hmmm
anway like you said the whole idea isn't bad - the realization is
Personally I like Resident Evil, Mortal Combat and Doom (it's not scary but it's good action movie though). I've seen Bloodrayne recently - that was crap! (it was like low budget version of Xena: The Warrior Princess)
Mortal kombat is great to trip out on when well, lets just say when THC kicks in .
Doom was an ok movie, shoulda changed the roll of the actors, The rock shouldve been the hero, best part was the first person part. I'd love to see a movie fully in first person. But then again, why would you want a movie like that when you can go out and buy doom or quake 4?
I havnt really seen that many movies based off games, I always thought tron the game was based off the movie.