Played through it all. All stars and badges. Even managed to get three stars on the last level. Almost impossible, you need to ram some opponents while they're not shooting.
Maybe add a boss rush mode?
Another pay game. By making it free, you could actually make more money due to advertising revenue shares. Consider making this a free game. 1/5 due to overwhelming pay content.
Maybe you should use your own sprites next time. Mission graphics are stolen from Tyrian. Game's fun though. 5/5 for gameplay, 1/5 for the blatant ripoff, cancels out at 3/5.
Ill try tochange it to space bar