The alien menace shows no signs of abating in XCOM: Enemy Within, the upcoming expansion to 2012's Enemy Unknown. Packed with new maps, aliens, and mission types, Enemy Within introduces a lot of additional content for all you alien hunters out there. At this year's Gamescom convention, I got the change to spend some quality time with the new mechanized exoskeletal cybersuit class, and chat with the developers about its role on the battlefield. But before we dive in, get the lowdown on all of Enemy Within's features in this comprehensive news story. Are you finished? OK, let's meet our new, mechanized friend!

Man or Machine?

Similar to the heavy, support, sniper, and assault classes, MECs are another trooper class with their own weapons and abilities. However, they are not randomly assigned to new squadmates; they're built, but we'll get to that later. These hulking units can best mutons in arm wrestling and squash sectoids by the dozen, but their considerable size prevents them from receiving any cover bonuses. When a MEC enters the fray, it's there to win…or limp out of the enemy's line of sight should things go south.

A MEC's size is matched only by the amount of damage it can dish out. In addition to choosing from several different primary and secondary weapons, these units can augment their arsenals through new skills, such as a grenade launcher or land mines. Of course, all this firepower is offset by a severe ammo dependency. In the demo I played, the MEC's weapons usually needed a reload after only three or four shots.

To build a MEC, you need meld: a new resource that appears as a collectible in certain missions. Having some meld unlocks a new research project, which in turn unlocks building the cybernetics lab needed to build MECs. It should be noted that cybernetics labs count as workshops when determining adjacency bonuses. Once this structure is up and running, all that's left is selecting a solider to have his arms and legs removed and refitted with cybernetic implants--including a very monotone, RoboCop-esque voice.

While collecting meld and unlocking its subsequent research is something you can do early in the campaign, the costs (both in time and in resources) are very high. MECs are a huge investment, and likely won't be a viable option for most players until the latter half of the game.

MECs on the Battlefield

Subjecting one of your soldiers to MEC augmentation removes his class, along with any skills tied to that class, and replaces it with the MEC's. For example, if you sacrificed a sergeant-ranked solider, you would get a sergeant-ranked MEC, along with the ability to purchase skills from the first three ranks. Overall, the MEC's skill tree is divided into two categories: fire support (offense) and survivability (defense). Fire support grants you additional weapons and tools to use against your enemies, while survivability increases the MEC's durability and gives some interesting defense tools to your allies.

On the battlefield, these units excel at environmental control. No, I'm not talking about weather control; I'm talking about destroying, circumventing, and, in some cases, even creating cover. The highly satisfying flamethrower, for example, can travel over cover and send the enemies behind into a panic, as well as set certain terrain types alight, creating an impassible blaze.

While I had fun playing around with this new class, I quickly discovered that a MEC's durability should not be mistaken for invulnerability. Yes, they have a lot of health and are fun to march straight up the battlefield and into an enemy's face, but they're also easy to overextend if you're not careful. All too often I found my MEC facing down a half-dozen foes, while its teammates were too far back to assist. XCOM is a series built on the importance of synergy and teamwork, and this new class is no exception.

Notable Abilities

Collateral Damage: This skill costs an entire ammo clip and destroys several sections of cover while damaging the units within. This was great for exposing groups of enemies who were clustered together, or creating new line-of-sight opportunities for my squadmates.

Kinetic Strike: This secondary melee weapon deals a ridiculous amount of damage to units directly in front of the MEC. This weapon complements the unit wonderfully since it doesn't run out of ammo, and plays to the unit's strength of being a frontline fighter.

Proximity Mines: These land mines are great for dealing damage and protecting your flank. A well-placed mine can tell you if a sneak attack is headed your way--just listen for the explosion--and they're also smart enough not to be triggered by teammates.

Inherited Perks: Each MEC unit remembers fragments of its previous life as a sniper or support or whoever, and gains a special perk based on those memories. A sniper-turned-MEC, for instance, gains the platform stability perk, which grants it additional damage for a turn if it doesn't move.

Giant cyborgs aside, there is still plenty of content left to explore in XCOM: Enemy Within. Stay tuned to GameSpot for our ongoing coverage of the game, as well as all the latest coming out of this year's Gamescom convention. Enemy Within will launch November 12 in North America for the Xbox 360, PlayStation 3, PC, and Mac.