6. Eternal Darkness
Easily one of the best and most underrated games of the GameCube era, Eternal Darkness: Sanity's Requiem was a highly original video game that teased the player by causing them to question the nature of the very game that they were playing. To screw with the player, the screen would often go scrambled, and the GameCube boot screen might even appear, a superbly unsettling and ground-breaking way to convey unease. The movie rights were bought in 2003, and though it would certainly take some tweaking to work as a film, there's no doubt that the level of creepiness could transpire through to the cinematic medium. Given how stagnant the horror movie genre is, and how well survival horror video game adaptations tend to do at the box office, this could be a tremendous recipe for success, even if Eternal Darkness is nowhere near as popular or recognisable a name as, say, Resident Evil or Silent Hill.