Arrow keys, space to shoot, and watch out for the boss's diamond form plus attack. This game is probably glitchy so please report bugs. Work in progress. It isn't done. BTW you have to press green flag 2 times to start. Fun glitches I'm no removing: spam space and your attack could go further.
A little credit to @godmaster3 for some ideas and Echo Mans moving code. I am working on: Background, title screen, cloud scores, loading screen, and a lot more!