Video and computer games usually don't do well as film adaptations, and there are many reasons why this could be (see one of my previous questions).
However, if it were done correctly - meaning it had the right cast, director, producer and screenwriter, was loyal to the source material, and no political pandering was involved - what video or computer game would you want to see adapted into a film? Or a miniseries?
Whom would you want to play the characters?
If done correctly, I'd be interested to see a StarCraft adaptation.
There are so many different characters and storylines, so I won't list them all here.
There have also been, to my knowledge, two attempts at Doom. Neither of them have been very good. But with the right team, I'd be willing to give it another spin. Maybe with John Cena as the Doom Guy.
Grim Fandango. Seriously, look at this picture:
... can you honestly say you're not intrigued? Casablanca in four years across art deco Mictlan with flaming nuclear demon beavers! And it's an adventure game, which has a linear story and a coherent (if kinda complex) plot; adapting it would be fairly easy.
Unfortunately, it was a LucasArts game, which means it's in Disney's hands now, and I trust their ability to do it justice like I trust Abraham Lincoln to be behind the Kennedy assassination.
If it's possible to crap on a childhood memory, Disney has or will shortly.