Hi. Your game is simple and fun, but while playing I found a way to cheat a bit.
When you're playing, hold the window bar with a mouse like you would like to move it, and wait like this for a bit. The game will freeze, but music will be still playing. When game is like this, spaceship will be "moving", but no collisions will be detected.
If you want to fix it, put the event loop to other thread, I've got my own fix, if you're interested.
Good luck with improving the game!