This is probably the best overlooked game in a long while. The imagination and emotional impact, the very real but very artistic style creates an illusion that is stuck in my own dreams for years to come.
A true classic that goes mostly unknown, which is pretty much Tim Schafer's MO. I remember being blown away by the cleverness of the level design when I first played it. There's a demo on Steam the lass time I checked. What are you waiting for?
A 3D platformer with incredibly creative level design. Sure, there were some minor control issues, and the music got a little annoying at times, but the levels, especially in the second half of the game, are mind-blowingly awesome.