I feel dirty for putting this on here, but I'm one of those people who doesn't believe the game is truly beaten until everything's been done. So if I don't get all the achievements for a game, I have to keep playing until I get everything. It's been like this since Mario Bros 3. I had to beat EVERY level if I wanted to feel like I had really beat the game. Now that they've added achievements, it's made it worse. I can't stop playing TF2. There are too many damn achievements.