Deus Ex (it really needs to be told again and kept alive because it's the single greatest conspiracy theory story ever created)
Half Life - because scifi/zombie/monster movies have lacked one thing more than any other. Head Crabs. We need more Head Crabs.
Mass Effect - could potentially be the new star wars.
Broken Sword 1&2 - 2 of the best Crime/corruptuion stories ever put into game. Brendon Fraiser for George Stobbartt.
Grim Fandango - for obvious reasons, get Depp, Burton and Carter, make it rated 15 and up. Perfectomundo.
Bioshock, if done correctly - definetley make it rated 15 and up.