You are in the middle of a battle and it looks like you have the upper hand. So you select a couple of your units. When you are done with your units you accidentally hit ESC twice, oh, it looks like the game just QUIT OUT. There is no way to get back in the game. Not only that but steam still thinks you are playing the game and wont let you re-open so I have to restart it.
Who thought that double tap ESC would be a good force quit button?