Back in 2014, I ran a marathon session of Gears of War to raise money for Child's Play. We ran nonstop, playing on Insane. It was as ridiculous as it sounds.
The big achievement, however, was when we finally killed Raam in the first game. Up until that point, I hadn't done that. I'd finished the game on Casual and Hardcore, and I had completed everything in Insane UP UNTIL killing General Raam. Until that stream. It was about 5:45 in the morning, and we had spent about an hour and a half working on him. There was a group of us, and we were taking it in shifts. I had just woken up, so I was refreshed and ready to take on the challenge. It was two of us, working in tandem, and we finally pulled it off. We couldn't cheer or anything, because I didn't want to wake up my roommates. That and @itsapril probably would have killed me, too.
Overall, the drive was reasonably successful. I hadn't been streaming for long, and we went for a whole weekend straight. We started at noon on Friday and went until 9:30 PM on Sunday. We cleared the first two Gears games, and got to Act III on Gears 3. We died 1,254 times. Yes, we kept track.
So yeah, that's my achievement story. If I spent a bit more time, I could probably come up with others. But this was what I remembered first.