I always feel uneasy when I think about XCOM’s enemies. Sectoid Commanders, Mutons, and Cyberdiscs are the stuff of nightmares thanks to the countless men and women I’ve lost to them. Much to my horror, developer Firaxis Games didn’t think the aliens were enough punishment, so it decided to add a new kind of foe who, unlike the ones mentioned here, is very much from our planet.

The XCOM: Enemy Within expansion (out Nov. 12) introduces us to Exalt, a nefarious organization that’s clearly on the alien’s side. This is in addition to the new weapons, mech class, resources, and other adjustments Firaxis announced back in August. PC players can download it for $29.99, but XCOM fans on consoles will have to grab it on disc in the XCOM: Enemy Within Commander Edition for $39.99.

Nothing will carry over from your old save files. Instead, you start a fresh campaign featuring the alien invasion story from last year’s XCOM: Enemy Unknown with the new content built-in.

Let’s take a look at why Exalt is so deadly.

XCOM: Enemy Within

Above: Exalt maintains a strict guideline of dress shirts, nice shoes, and pinstripe pants.

Image Credit: 2K Games

Meet Exalt

Like XCOM, Exalt is a paramilitary organization that operates in the shadows … but its goals are drastically different. It believes that the aliens’ genetic experimentations are a good thing — in fact, it wants to help them — and it wants to rule the world. Exalt sends sleeper cells to different countries (the same ones XCOM monitors) to advance its pro-alien agenda.

To combat this threat, XCOM now has access to Global Covert Operations, a branch of missions that sends in a single plainclothes soldier (armed with nothing more than a pistol and a grenade) to secretly investigate the cells. Completing these missions earn you clues to the whereabouts of Exalt’s headquarters. Once you find its base, you can send in a squad to destroy the organization once and for all. You can also try to ignore them. While letting Exalt run freely will hurt you in the long run, defeating them is optional — the extraterrestrials are still your primary objective.

“This gameplay is something that we felt XCOM needed, in the sense that this is a campaign that the player controls the tempo of, to a certain extent,” said lead designer Ananda Gupta to GamesBeat. “Unlike the alien invasion –where UFOs will come in, you shoot them down or fail to, abductions and terrors occur, and you have to deal with them using what you got — here, you can choose your tempo. You can choose your posture with respect to Exalt.”

XCOM: Enemy Within

Above: With hardly any equipment or heavy weapons, your covert agent is vulnerable. It’s best to get him out of there as quickly as possible.

Image Credit: 2K Games

Why Exalt is such a pain

Fighting Exalt adds yet another strain to your limited resources. If the sleeper cells go unheeded, they will disrupt XCOM operations every chance they get: Propaganda missions raises a country’s panic level, Sabotage drains some of your cash, and Research Hack delays any projects you’re researching at the time. The best way to stop them from carrying these out is by revealing their locations before they can act. You can spend some cash to expose them with an Intel Scan — causing them to look for a new place to hide — or you can avoid that expense and wait until they launch one of their operations, which ends up revealing their location anyway.

When you know what countries the cells are in, you can start sending in your covert agents. They need time to gather intel, and once that passes, you have to send a squad to extract them. But Exalt won’t let you go that easy, so you’ll have to fight the cells in turn-based battles (you control both your squad and the agent you sent in earlier ). Enemy Within randomly chooses one of two objective-based modes in these situations. In Covert Extraction, the agent has to hack into Exalt’s communication relays (disabling Exalt’s main attacks for one turn) and get to the extraction point alive. Covert Data Recovery is a King of the Hill-style mode that has you protecting a series of control points while killing all the Exalt troops in the area.

The guys I fought against in the demo were regular Exalt soldiers — some have genetic modifications, or G-mods, a feature in Enemy Within that upgrades your soldiers with new skills in a Genetics Lab. These guys carried the same sort of weapons as I did. Later on, you’ll face elite Exalt soldiers who have better equipment and G-mods you don’t have access to.

“We did do a lot of work on [Exalt’s] A.I.,” Gupta said. “They combo their abilities and use their explosives a lot more smartly than the aliens do. … We wanted to create a new combat experience.”

“Smartly” is a bit of an understatement — they’re relentless. Every time I had my XCOM soldiers near each other, Exalt never failed to lob a grenade or shoot a rocket at them. Two of my guys died before I realized I needed to keep them further apart. And whatever advantage I had from the beginning quickly disappeared as more and more Exalt reinforcements came in after I hacked the relays. Coupled with catastrophically poor shots from my team (apparently, I was the first person to miss with a rocket launcher that day), I had no choice but to make a hasty retreat.

Sadly, not everyone made it back to the plane. I made the hard decision to leave my sniper behind because he was too far from the extraction point and an entire squad of Exalt men were practically breathing down his neck.

Sorry, buddy. It was for the greater good.