A long time has passed since I played really original videogame. Now, here is "Cursor 10". From Japan. In black & white. Featuring single-player cooperative mode.
At first, you may be dumbfounded what the hell is that graphics supposed to mean but believe me, it's no joke, it's a real game with great premise that becomes apparent after minute or so of playing.
UPDATE: Also, check out the best freeware games of 2007.