Use the <- and -> to control your rocket ship. Press the up arrow to boost. The longer you boost the more multiplier bonus you get. Press space to shoot and avoid the enemies. When you shoot you use up points, so be careful don't run out.
I made this with one sprite, so it is not as complicated as I would like. Feel free to use my code (it sucks, so don't know who would use it) but please credit me (I want to be famous!!!!). Enjoy! I put a lot of work into it!