From Valve Developer Community
It features 6 chapters, 8 different enemies, 5 weapons and a full-fledged buggy.
The game also includes a highscore system with network support and a bunch of funny secrets.
NOTE: Codename: Gordon has been discontinued from Steam, as the developer, Nuclear Vision, Has gone bankrupt. their former website is coded into the game itself, and said website has been repossesed.