A/D=left and right turn W/S=go faster, slow down space bar:shoot Q:missile Z:mega missile E:shields If your score is 15 then there will be a boss. If your score is 30 there will be another boss. If your score is 45 there will be a third boss. If your score is 60 there will yet be a fourth boss.
This took me a lot of time; a love and/or like would be great. Please feel free to remix. Please leave a comment so I can see what to improve. Thanks to WebCoyote for helping me.