An entire mod developed in a week. Is it possible? We just proved it was. An enjoyable mix of ego-shooters, fast-based CTF gameplay and team base attack/defend. The progress is available on the Facepunch thread.
It's in the SVN but not any of the updates, so, yeah. Pretty small symetrical map.
This map is a piece of ****. How it got into the SVN I'll never know.