Steam's XCOM: Enemy Unknown Page is now accepting pre-purchases of Firaxis' upcoming continuation of the X-COM series of counter-UFO strategy games, which includes an unusual program that offers customers increasing levels of rewards as more of them commit in advance of the game's release next month. The page also now offers a demo of the game playable through Steam. This announcement has more details on pre-purchase incentives and a special edition of the game at some retailers, as well as the following explanation of what to expect from the demo:

Gamers who download the demo will be guided through two levels of the single-player tutorial campaign, experiencing the combat controls and effective tactics for defending humanity against the alien threat. The two tutorial missions will also introduce players to the XCOM base, where soldier training and researching alien technology takes place, and offers a chance to experience the tactical and strategic layers of XCOM: Enemy Unknown. The XCOM: Enemy Unknown playable demo will be available soon for console gamers.