I'm just going to chuck in my choices for no reason here:
Crimson Skies:
The Indiana Jones of the air- on the surface it's death defying dogfights inbetween zeppelins blasting broadsides at each other, but look closer and you've got a genuine story of intrigue, double crossing and a climax to save all the citizens of Manhattan.
The Xbox sequel could sort-of work too I suppose, though not nearly as well.
Driver:
An undercover cop story de jour- on the surface it's a chain of expertly choreographed 70's car chases in the vein of The Blues Brothers, but look closer and there's a constant tension as our man Tanner gets closer to the top of the Crime family to find out just what they're up to. Think Donnie Brasco on four wheels.
The Saboteur
Inglorious Basterds meets The Dirty Dozen in this tale of one man's vengeance amid the turmoil of Paris under the Nazi occupation. There's a involved, intriguing and sometimes quite funny story to be told here, with enough Nazis getting blown up, riddled with bullets and having their necks snapped to make Where Eagles Dare look like The Sound of Music.
Mafia: The City of lost Heaven
Does it really need to be said? You could simply shot-for-shot remake all the cutscenes and condense the gameplay of this masterpiece and it would still produce something that'd eat The Untouchables for breakfast.
Star Wars: Dark Forces OR TIE Fighter
Good points about Battlefront, and I too am sick of seeing lightsabers and want more focus on the little grunt guys. But why not adapt something that people already actually love? i.e. the two greatest story based Star Wars games ever made before Battlefront came along?
Left 4 Dead
It'd have to be the No Mercy campaign of course. Leave the others for movies of their own. And don't forget the humour!
Everything or Nothing
The best bond film never filmed. Get Pierce Brosnan back for it too. I don't care HOW old he is!
Perfect Dark
The game that Aeon Flux wanted to be the movie of. Bonus if you can get Keira Knightly to go all Domino mode as Joanna for it...