I was wondering if anyone could identify, or do their best to identify, the weapons in the video game Shadow Complex.

http://xbox360.ign.com/objects/839/839087.html

From what I can make out, there is a Walther P99, a Heckler & Koch MP5, and an M4.

There are only five weapons in the game, and one of them appears to be completely fictional, whereas the other four of them appear to be based off of real-world weapons.

Thank you for your help.