Over the hump
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
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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
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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.