More than just a bit of downloadable content, XCOM: Enemy Within is a massive expansion to Enemy Unknown. While you will be able to download it on the PC, the only way you'll be able to play on the PlayStation 3 and Xbox 360 is by buying the disc-based Commander Edition, which comes with the original Enemy Unknown, too. At least it'll only be $39.99 for consoles ($29.99 on PC).
The trailer above shows off a bit more of what to expect from the new content, including our first look at EXALT. The group is a rogue organization trying to undermine XCOM, and use the alien technologies for their own advantage. XCOM: Enemy Within is due out on Nov. 12.