http://www.drmdatabase.net/database/drm-free-games
This list is full of wrong claims. Some people think if 3rd party DRM is removed, game is automatically DRM free in Steam which is wrong because majority of them have Steam DRM (stub or CEG). What's worse, there are games on the list which start perfectly fine without Steam client pop up, but you need to enter CD key.
AI War Fleet Command on this list is wrong. It doesn't have Steam DRM, but you need to enter CD key after which is DRM free, but this is not pure DRM free. The same apply for other Arcen Games games and for non-Steamworks Stardock games after you register them. More games with Steam DRM:
Sacred 2: Gold, Star Wolves 3: Civil War, Steel Storm, Darkstar One, and probably more. I'm testing games, but you get my point :-).
Or BS like this DCS: Black Shark which has StarForce ProActive DRM.