here is my litle demo scene, basically just playing around with the projectile, and doors.
http://www.creativecodingstudios.com/Unity/index.php?show=demoman12/JJJJJ
i like the projectiles but the doors need work, i found myself running into them with my gun sticking inside of them. Make them trigger sooner and put a limit on how close a player can get to them until they are open. Also the stairs are unusable.