RyaNtheSlayA wrote:Half Life 2, and Half Life.
Half Life is definitely intended to be creepy, with dark passageways and head-crabs jumping out at you.
I'd say Super Mario Bros 2 though. Despite being colourful, the whole thing doesn't feel like a Mario game. The setting and music is all kind of Arabian and the gameplay is completely different. It all makes the game kind of unsettling. Also, need I say more?