Has anyone played
Penumbra? It looks interesting, and the reviews are pretty good. It's supposed to be influenced by Lovecraft, which is always a plus for me. The most interesting part is the physics, though. Quoting from one review:
You physically build your own survival. You actually hand-make the barricades, the weapons, the ladders and escape routes that you will need to survive...and you do it with movements and manipulations just like in the physical world.
And you can get all three games in the series for $5, just for this weekend.