The Only Good Bug is a Dead One.
Good idea for a game but the layout was a little counter-intuitive. I took me a couple lives to figure out that the ufo has to be shot in order to remove its missiles from game. I liked how the progression wasn't forced, but at the same time it allowed me too much time to get upgrades. I ended up on the last level of your game, against the very last super nuke with 4 health bars, but suddenly my cannon stopped working and the game restarted back on level one. Is this a glitch, or did you not expect anyone to get that far? Anyways, im sure if you clear up this issue of indicate why this is happening in the instructions, I think you will have yourself a solid game.