First of all, you need a way to start the game that isn't mouse-based if the controls don't use the mouse and you are instantly thrown into action. As for the action itself... what can I say, there isn't much. The same characters run at you over and over. There does not appear to be any increase in difficulty. The enemies do not approach in any other way or try to evade fire. There is no reason for the ghost to be able to jump, or even move for that matter. I found that alternatively firing left and then right kills every enemy for as long as you are willing to repeat, often before the enemy even appears on the screen.