I ran out of ammo pretty quickly, and didn't get any coins. Until one time, after reading another jammer's feedback, I realized how the game got its name. The coins appear far away from where you kill the enemies, they're hidden. It would have been nice if the game could have told me that, or maybe made it so that the first coin that appears does so on the screen, but not too close to the player or the enemy, that way the player can see that coins appear in weird places, and knows to search for them by walking around. The music worked (but was a bit short) and while the shooting sound effect worked, it would have been nice to also have a sound effect for dying.
Also, minor glitch with the credits screen: clicking to exit it puts me back at the menu but immediately jumps back to the credits screen. I think you should detect the click on the buttons in a different way to avoid counting one click as two.