Call of Duty may be a blockbuster success on a global scale, but Activision's cash cow isn't quite bulletproof. For example, Epic Games is taking shots at the franchise with Duty Calls: The Calm Before the Storm, a free downloadable game parody that mocks the military first-person shooter and a number of its gameplay conventions.

　　The difference between Duty Calls and its inspiration becomes apparent as soon as players start the game. Upon being dropped into a level, a voice gives the player marching orders over the radio.

　　Look familiar? "Here's your objective," the commanding officer says. "Blah blah blah blah secret base. Blah blah blah blah plan. Blah blah blah nuclear missile bomb. Blah blah blah counting on you. Utmost importance. Win. Good luck."

　　As players make their way through the game, they find useless objects (a stick, loose leaf paper), run into villains who can be beaten only in slow motion, and achieve the rank of Sergeant of the Master Sergeants Most Important Person of Extreme Sergeants to the Max. The game isn't exactly subtle about its critiques, as every one of the player's gunshots is accompanied by a voice clip loudly saying, "Boring!"

　　Although the game's parody is pretty apparent, its purpose--promoting Epic's upcoming shooter Bulletstorm--is less overt. Up front, the biggest clues at the tie are the game's subtitle and a plug for Bulletstorm in the description section of a YouTube video on the official site. A short commercial for Bulletstorm also runs at the completion of Duty Calls, which can be finished in about five minutes.

　　Developed by Epic subsidiary People Can Fly, Bulletstorm is a first-person shooter built around a skillshot system that rewards players for dispatching enemies in creative and often gory ways. The game is set to launch for the Xbox 360, PlayStation 3, and PC on February 22. For more on Bulletstorm, check out GameSpot's previous coverage.