Good concept, it reminded me of jumping puzzles from the Guild Wars 2, which I enjoyed a lot. I liked the idea of being able to select any level, especially since some levels area quite difficult to do. The last level was the most fun for me, moving platforms add some nice dynamics to otherwise static levels.
The gravity seems a bit off though, falling down feels more like flying or diving.
And the gun doesn’t seem to have any fire animation or sound effect. At first I thought it wasn’t working, but then I noticed that it actually hits the targets.