Fun endless gameplay! I like the short immediate learning curve and after that you really feel in control. I think a difficulty progression would add to the experience.
I really enjoy the simplicity of the core mechanics, I think new secondary mechanics can elevate the player experience. E.g. More NPCs? Maybe animals are running around in this bush too, and you wouldnt want to shoot them. Lightning, providing random flashes of light in the difficult levels etc.
Good job!