Just got my ass kicked up and down the street in a Classic Ironman run. A pretty good start gave me a squad of survivors who were beginning to rank up fairly well, plus several "alternates" which are still better than rookies.
Then I got hit with a terror mission. My best dude got ambushed by two crysallids (overkill: he died in one hit), which then jumped through a hole in the roof to attack my only assault (she missed her close quarters attack somehow and got killed). This left me with a suddenly-useless sniper (she didn't hit a single target in that entire mission) and a support against at least six of the damn things, with more being transformed in the shadows. They were surrounded and torn to shreds, despite making good use of grenades to bring a couple wounded ones down.
Thus began the decline. My alternates were a waste of time, dying in droves until I was down to one man. Seemed like every single mission loved to throw at least six aliens at me simultaneously, all of them Thin Men and Floaters. I managed to rally a little once I built some carapace armor and laser weapons and undertook a last-ditch recruitment drive, finding a team that actually managed to survive two whole missions without a scratch. Then they all died against an army of Thin Men (I counted at least twelve) with high ground, high cover, and plenty of half-cover explosives between me and them.
Country after country left the alliance, but I managed to survive until the end of the month. I cranked out an elerium generator, the Officer Academy, upgraded my weapons; anything I could think of to stave off disaster. None of it mattered, as the Cyberdisks chose this time to show up. TPK after TPK, I was finally left with just four men. The last four men. I couldn't even afford more recruits. It had gotten so bad, I nearly sobbed with relief when the four went on a mission and met Sectoids. I pulled my troops back, hoping to lure the wimpy greys into an ambush. That's when three Thin Men and three Floaters showed up. One man was killed in a single shot, despite hiding behind full cover and from across the maximum visible distance. The other three missed their reaction fire against a single Floater, which critically wounded another.
The last two had a shining moment of glory which I still can't believe happened. Somehow, they each nailed an alien at 25% hit odds on the same turn. Return fire missed entirely! This time, they each made another kill at 65% odds! This was it! These last two survivors were gonna do it!
Cyberdisk shows up. One of the survivors is gibbed instantly. The other panics and hides, prompting a Thin Man to walk up and execute him point-blank. A few days later, XCOM is shut down and the aliens take over.
tl;dr, FUCK YOU, THIN MEN!