Understandable, it is not for everyone. I hope you weren't too frustrated. But you can press 'esc' to quit the current run.
Nah, I know I'm not good at this type of game. I doesn't really effect my rating either, maybe just a star less for gameplay.
I think I did use 'esc' to quit the run, but didn't find an option to quit the game. Had to use the 'Close All Windows' option.