A small update making it possible to stop and leave the game by pressing escape key first, then firebutton to leave or escape again to continue. No need to use your lives up first.
Before it was neccessary to use Alt+F4 to instant-quit. You could not abort on arcade machines back then as well but it might be inconvenient if you really need to leave your pc. So, now there is the escape-menu ingame.
More updates later.