That sounds like a weird bug. I haven't seen anybody else reach the 400's, so that sounds really weird as well. Perhaps something weird happened with the collision detection? Maybe you fell through the floor collision on a single frame? Getting ground collision working out to infinity was a challenge I spent some time coming up with a clever solution to, so it's possible you found an issue with it. So far your comment is the only one mentioning this issue, so you get the credit for breaking my game.