This is a well-executed top-down shooter with fun graphics. I noticed a few sprites seemed off-center - when the shadows appear under falling enemies, the enemies seem to spawn on the bottom right corner of the shadow instead of the center. Also, the gun sprite rotates in the top-left corner of the frog sprite, instead of in the center - not sure if this was intentional.
I couldn't find any powerups so could not rate this on on theme. But I liked the defense concept of the game and the graphics.