It's not due for release until early 2011 but it looks like GameStop has a special pre-order offer if you get Portal 2 from the retailer. Buying Valve's upcoming puzzle shooter ahead of its release from GameStop will not only net you a $5 discount from its normal $49.99 price but it will also get you some "custom bots" for the game's co-op campaign.

By the way, the release date for the game that's currently shown on the GameStop site is March 31, 2011. According to what Valve told Big Download via an email today that date on the site is incorrect. Portal 2 is still scheduled to be released on February 9, 2011.