This is one of the coolest prototype games I have seen in aaaaaaaaaages! The Unfinished Swan is a first person shooter - but unlike anything you’ve ever seen. More accurately it’s a first person painting game set in an entirely white (ok, sometime black) world. Players splatter paint to help them find their way through a rather unusual landscape.
Check out the website here. Theres also a pretty cool video you can watch that demo’s the gameplay.