Fun and time consuming
This is a great game. I liked how the enemies moved in zig-zags to make it harder. I like your drawing style also, and you did a good job making it simple and adding a high score table. My high score was about 36000, I just quit after that, I'm not completely sure but I think at that point it didn't get any harder, maybe you should change that. A cool thing would be to make another version with buyable guns between levels and more variety. But this game is amazing.