A playable demo of XCOM: Enemy Unknown is available to download on Steam now, 2K Games has announced.

The demo offers up two levels from the single-player campaign, introducing players to the combat controls and the XCOM base, used for soldier training and to research alien technology.

Head over to Steam to check it out.

The demo will also be available to download on Xbox 360 and PlayStation 3 "soon".

XCOM: Enemy Unknown is a contemporary update of MicroProse's classic turn-based strategy series, headed up by Sid Meier and his team at Firaxis.

The game lands at retail on October 12 on Xbox 360, PlayStation 3 and PC.