Pros: Easy to understand controls, the shooting and reloading mechanic were good and the targets moved at a variety of speeds (which added a challenge which I felt was also good), the moving trees and grass was good that added a sense that there was a wind blowing through the area, the environment itself I felt is a good starting off point (if you plan to take this game further), the bullets holes were also a good idea (though I feel when shooting the grass, the holes shouldn't look the same)
Things I felt needed improvement: Once you've dropped a gun the ammo count still shows on the screen, you can shoot (and 'kill') the targets despite not holding a gun, the sounds of the last gun gave me a scare because of how loud it was (that may have been my fault though), there is no sound/music (except for the guns, footsteps (the sounds of jumping and landing need a tweak because they sound a bit off to me) and the main menu wind sounds), the Settings and Credits don't work (though that might be added later), the guns don't face the reticle and they even move direction when moving the camera up and down.
Conclusion: I do like this prototype and I like the direction you're going for, however, I find that there are still some issues that hold it back a tad. A five or six out of ten for me.