The former imbues soldiers with passive buffs. Though some new items-such as ghost grenades, which turn your soldiers invisible for a turn-open a surprising amount of strategic avenues during battles, the real highlights are gene mods and MEC Troopers. Of course, the enemies of mankind aren't the only ones who get some new toys. Guess which nation they're based in correctly, and you can invade their HQ and shut 'em down guess wrong, and whoops, Canada just backed out of the council. As you complete EXALT missions, you'll gradually gain clues as to where their headquarters is located. As if it weren't difficult enough to keep the world's nations from bailing on the XCOM project-thus decreasing your base's monthly income and by extension the survivability of your troops-hidden EXALT cells will crop up without warning, sending terrorized nations over the edge. While fighting EXALT forces is only sort of fun, they play a far more interesting role in Enemy Within's so-called 'strategy layer,' where they contribute to global panic. Instead, you'll have to buy a pack-in compilation that includes both the core game and the expansion for $40-a pretty sweet deal if you haven't played it yet, but a bummer if you have. If you're a console gamer, you can't buy Enemy Within separate from the main game. The thing is, if you've already purchased Enemy Unknown on PC, this expansion will run you an additional $30. Alright, so Enemy Within is pretty great, and is no doubt the definitive version of Firaxis' XCOM reboot.

Xcom enemy within vs enemy unknown