Bioshocked: Demo pops up on Xbox Live marketplace without warning

A demo for the highly anticipated first-person shooter from 2K has shown up on XBL marketplace.

A demo for one of the most hyped games of the year showed up on the Xbox Live marketplace Sunday night to the surprise of many.

The demo features a tweaked version of the first 45 minutes of the game, allowing players to experience more weapons than what you'd normally start out with.

Xbox Live immediately suffered massive slowdowns as word quickly spread about the chance to take a sneak peak at what is sure to be one of the best games of 2007. There has been no word on whether or not PC fans can get a taste of Rapture, but we'd imagine a Windows demo will be coming soon.

Bioshock launches August 21 for the Xbox 360 and PC. A limited special edition is being offered for both platforms and will include a behind-the-scenes DVD, a CD with the Bioshock soundtrack, and a Big Daddy figurine (the lovable gentleman seen in the box art above).

Check out Bioshock screenshots here.