Youtuber Antti Kokkonen, who uploads Let's Plays to Youtube under the username Zemalf, is one of the best XCOM players in the world. On January 11, he finished a 50 hour run of XCOM: Enemy Within on Impossible Ironman difficulty without losing a single country. Or Interceptor. Or mission. Or soldier.
It was a perfect run on the game's hardest difficulty (and his first time through Enemy Within). On Ironman, XCOM is limited to a single save file. No do-overs. Beating the game on Impossible Ironman is a rare feat, but beating it without losing a single soldier? That really does sound impossible. But Zemalf did it, and he recorded it all across 58 Let's Play videos.
"I consider myself an okay player, but the run did go really well," he told PC Gamer. With Zemalf's help, we've broken down this achievement in XCOM mastery, dissecting his 58 part series into the key moments that defined the run.
As the XCOM faithful know, Enemy Unknown and Enemy Within operate on a reverse difficulty curve. They're brutally unforgiving in the early missions, when soldiers are inexperienced, panic easily, and die to a single alien blast. "The first five to ten missions are crucial," Zemalf says. "In this run I should've lost, or could've lost, a whole squad in a very early mission where I more or less played really badly. But just out of luck I didn't lose anyone."
If there's a consistent theme through all of Zemalf's run, it's luck. Luck in the missions the game generates, the panic levels he has to contend with, and the soldiers he starts with. And when luck fails him, Zemalf falls back on his slow and thoughtful playing style, methodically considering every option before making a move. He narrates his Let's Plays the same way, speaking in a deep, calm voice.
We've incorporated some of those LP videos below, timestamped to dramatic and crazy and revelatory moments in the run. Watch them as you read for examples of Zemalf's strategy (and some very, very lucky breaks).
Chance gets Zemalf out of more than one seemingly impossible situation. Early in the run, he's offered a council mission with a killer reward: five engineers, the equivalent of an entire workshop add-on to XCOM headquarters. He has to go for it. Fifteen minutes into the mission, though, things are looking bad. One of Zemalf's soldiers has already taken a hit and is down to 1 HP. And when he moves that soldier forward to deal with a lone sectoid, he accidentally reveals and activates two more (watch below now) .
At this point, the sectoids get to take two shots at his sniper, who is perilously vulnerable in half cover. They miss, granting Zemalf another turn. He misses his first shot. His second, which needs to kill a sectoid, drops it down to 1HP instead. Then he makes what should be a fatal error: he presses the wrong hotkey, accidentally telling his third soldier—now dangerously exposed—to take a low-percentage shot. It misses.
He stews on it for a minute with only one move left. But that last soldier, the sniper, ends up saving his bacon.
"In most cases I took an educated guess or calculated risk moving into certain positions, knowing if I activate a group here, I can deal with it, like having a heavy with a rocket ready to shoot," Zemalf says. "I was always thinking ahead to activate aliens with moves left." At least, almost always—he admits that on a few occasions, like the one above, those calculated risks got him in trouble.
A couple LPs later, Zemalf encounters his first UFO crash. Some risky advances pay off by not revealing additional aliens. If they had, he would almost certainly lose two of his soldiers. But this mission, which he calls the most tense situation of the entire playthrough, shows off the side of XCOM that can be maddeningly difficult: missing high-percentage shots (watch below now) .
The encounter starts out easily enough, with one alien totally exposed and at 1HP. But an 85 percent shot misses the mark. And then a 71 percent shot misses. "Welcome to XCOM," Zemalf says under his breath.
A miss from one of the sectoids at point blank range keeps Zemalf's support soldier alive, but the next turn gets even uglier. He reveals three more aliens by advancing too far and spends several minutes considering every possible option.
"Looking back at it, I could've played a lot better, but that's easy to say now," Zemalf says. He makes a mistake by advancing too far, but this situation highlights Zemalf's strength as an XCOM player: he thinks through each strategic option before moving and only commits to the best course of action when he's sure it's the best. And when things get really dicey, XCOM pays back for its earlier cruelty by helping him land three moderate-percentage shots in a row. He wipes out four sectoids in one fell swoop.
Most of the time, Zemalf's aggressive strategy works well. He methodically activates a group of aliens, then tries to take them all out in one turn. He points to an encounter in his ninth LP as an example (watch below now) .
Since this is several hours later in the run, Zemalf already has a MEC trooper in his squad. He uses the MECs as tanks to take hits that his other soldiers wouldn't be able to survive. As he faces a pair of Thin Men, he methodically thinks through each of his soldiers' abilities, using the MEC's collateral damage ability to destroy one alien's cover, and a grenade to take out the other's cover. That gives him better odds of landing shots with his remaining troops, and he never has to leave cover to fire.
"It's kind of hard to describe my own style, but based on the comments I get, I think I'm playing more aggressively than many others," Zemalf says. "When I have activated alien groups, I play very aggressively to take them out as fast as possible. I think that was key in not losing anyone. The game doesn't get any chance because of the mechanic of how the groups spawn—if you can take the one group out that you activated, before they even get an action, they can't shoot you, and then you more or less can't lose anyone."
Being able to take out alien groups so expediently took some smart base planning early in the game. Zemalf aimed to get as many satellites up as he could in the first three months of the game, which would prevent the XCOM countries from panicking, leaving the project, and denying him crucial resources. He also rushed to build a MEC early and to research laser weapons, which he'd need to deal with the HP buffs aliens get on Impossible difficulty.
Still, it took luck to get him through those first few missions with inexperienced, ill-equipped troops. "Getting hit [early] and not getting a lethal hit is lucky, and I had quite a few of those early on," Zemalf says. The heavy soldiers' rockets and grenades help him get through those early missions. Later he favors snipers and assault troops over heavies, because their explosives could destroy alien weapon fragments he needs for research.
Zemalf's perfect run almost ends in the XCOM Council mission Confounding Light, which gives him 10 turns to outfit a train with transponders and send it down the tracks. The entire mission is tense; Zemalf has to push forward faster than usual, position his soldiers to activate the transponders, but still take out any enemies that could quickly decimate his troops. In the end, he's left with a single turn, a MEC one hit away from death, and isn't even sure he's going to be able to complete the mission (watch below now) .
Here at the 10 minute mark, Zemalf accidentally activates some Thin Men and his MEC takes its first hits. Things get worse for the rest of the run. Skip ahead to 45 minutes to see Zemalf play through the last clutch turn. "Please, please, please," he pleads with XCOM as he tries to activate the train. Again, luck is on his side—his MEC survives and he completes the mission with his last possible move.
Thanks to XCOM's reverse difficulty curve, he's over the hump by the middle of his 58 video run. Zemalf cites Confounding Light as the last mission he truly struggled on.
Enemy Within is, according to many players, a harder game than the original Enemy Unknown. It adds a resource called meld to maps that expires after a few turns, encouraging players to advance more quickly. It adds new enemies and missions. But it also adds gene modifications, which Zemalf uses to great effect.
"Something I think is borderline broken in the game is the mimetic skin gene mod," he says. Mimetic skin grants soldier invisibility and makes them untargetable. "Using the mimetic skin with the sniper, with squad sight, the aliens didn't even get a shot on me in many missions. [For the sniper], half cover counts as full cover and keeps them invisible. That was just ridiculous."
By combining mimetic skin with a sniper's Snapshot and In the Zone abilities, Zemalf was able to move his sniper and fire in the same turn. And with In the Zone, taking out a flanked enemy with the sniper lets that unit fire again. Zemalf could take out entire squads of enemies with a single sniper (watch below now) .
This mission occurs about three quarters of the way through the run. By this point, Zemalf's soldiers are equipped with mimetic skin, and he uses that ability to get close to the aliens without worrying about taking a shot. He deals with them easily.
By LP 45, Zemalf is around 30 hours into his Impossible Ironman challenge. He hasn't lost a soldier or failed a mission. But he doesn't go out of his way to preserve the perfect run. Instead of abusing mimetic skin and coasting to a (relatively) easy zero-deaths finish, he switches out some of his troops for rookies and trained them up.
"I actually played quite sloppily in the later missions and I didn't shoot for not losing anyone," he says. "I just wanted to play through, and that kind of ended up happening anyway."
Amazingly, Zemalf went into Enemy Within with little foreknowledge of the game. He had played Enemy Unknown, but started Enemy Within soon after its release in Europe, and only spent a few days watching streams on Twitch before beginning his run. He knew that MECs were in the game, but knew almost nothing about them.
"I had seen the new stuff in some previews, I watched maybe a couple videos, but I didn't know what abilities the mechs had. I just knew they had a lot of hit points," he says. "I can't say it was blind, but I hadn't played any of the missions."
If not for the player/audience dynamic of Let's Plays, Zemalf likely wouldn't have come through his entire Impossible Ironman run unscathed. Commenters clued him into the gene mods, and he did research which autopsies he'd need to unlock them. They also warned him about the XCOM base assault, so he knew in advance how it would work.
"I got the mission relatively early as I built the hyperwave relay quite early. Some people said I was really lucky because I only got sectoids," he says. "I kind of would have liked to play completely blind, not even know the base assault was coming."
Even with some help here and there from the audience, Zemalf did something few XCOM players could accomplish. And he did it better than most others who have completed Impossible difficulty, too—his game summary stats at the end beat the world average in every single category.
As the credits roll on his run, Zemalf reflects on his performance. "Little bit of an empty feeling as this draws towards the end. Little bit of sadness," he says. "But also happy that it went so well. And even more happiness at how much all of you have liked this. It's really something. I've always said that I'd be doing Let's Play videos even if just one person was watching, one person who enjoys them. And when there's a thousand, or several thousand, enjoying the videos, it makes it all even better. And the feedback that I get from all of you, that's what keeps me going. At times it was overwhelming. I was really happy to play this."
Zemalf plans to tackle the original X-COM: UFO Defense at some point in the future.