If you want a game completely unlike any other game ever made, try LSD Dream Emulator. It's a PS1 game based on a dream journal that a woman kept for 10 years. All you do is walk around in the dream world, inevitably discovering a bunch randomly-generated events. It's not something that you can describe well on paper, you really have to play it for yourself.
It was only released in Japan and in very small numbers, so you'd have to get a PS1 emulator and the ROM.