A lot of people are cheating all the achievements to get the Christmas achievement. The bottom 5 (Missile, Demon, Zombie, Girl, Impossible) were at 0.2% and now they're at 0.5%. Tis a sad day.
Yeah, but at least we know that the number was even lower than 0.2% and we can all feel good about our awesome achievements.
I'm just glad to see some life back in this game and these forums.
Edit: Actually, come to think of it... I have an alternate steam account that ended up with a lot of my achievements from this account because I logged in on the same machine. My iron boy achievements didn't unlock though, so it can't be as simple as copying the save file. There must be some other way they've discovered to hack them.
Edit 2: Looks like you can't get either Christmas achievement from the save file either. Good news.