People need to stop thinking so narrowly: there is no reason there can't be a great movie based on a game. Some video games tell amazing stories, but for some reason, they never actually hire good people to make the movies. I was going through that list and seeing games that could make decent movies, but they're hiring the same people that made crappy game movies in the past. LEARN FROM YOUR MISTAKES, YOU IDIOTS.
OT: I would see a Sims movie for one reason and one reason only: if the entire movie is in Simlish, with subtitles. That would be amazing.
I had high hopes for the Prince of Persia movie, then I heard they weren't doing a direct adaptation. What idiot decided we wanted to see some crappy spin-off? The Sands of TIme would make an amazing film! Some on, people!
Shadow of the Colossus could be awesome, actually, but not if they're getting the writer of The Legend of Chun-Li to do it.
Gears of War could be a fantastic war film.
Halo would be amazing if they get the right people. Well, they already had the right people, but if someone else really good takes it on.
Also, I will note that the movie based on Clannad sucked horribly, but the anime is guaranteed to make you bawl like a baby. Incredible show.