A good 'mindfuck' video game to play?

[Claus Gallardo]

Sanitarium, and the stanley parable are veeeeeery minfucking.

 

[Exhuminator]

http://www.gog.com/game/pathologic

http://en.wikipedia.org/wiki/Hellnight
(Dark Messiah in Japan, released in English in Europe as Hellnight.)

http://www.gog.com/game/i_have_no_mouth_and_i_must_scream

http://en.wikipedia.org/wiki/Deadly_Premonition

But the holy grail is always...

http://en.wikipedia.org/wiki/LSD_%28video_game%29

 

[TehCookie]

999 for the DS and it's sequel Virtue's Last Reward on the 3DS/Vita. There's multiple endings and when you get to the final true ending prepare your mind.

 

[Reven]

You might want to check out Afterfall: Insanity for the PC, it's an indie game and the voice acting isn't exactly great, but i feel that it's intro is definitely what could be considered a Mind-fuck, it's also relatively cheap.

There is also the game paranormal recently released on steam, which ranges from subtle and very trippy to overt and crazy.