Very Fun Game
Simple, but effective, and I like how you can pick the direction you shoot by holding the space bar.
I found a bug, which is the reason why I'm writing the review. When you get the Rocket Launcher, you can kill everything quickly by doing this trick - you shoot the machine gun till there's a line of bullets from one end of the screen to the other, then hit 4 to switch to the rocket launcher. Now every bullet on the screen is as powerful as a rocket. Something to fix in the future.