Very creative mechanic. I like the implementation of the theme. I also love the crossover of a precision platformer with tile-based movement. It added almost a light tactical element to the game when lining up your shot.
I will say, I feel like having your momentum stop mid-air by releasing a button felt a little clunky. I almost wish your momentum would stay, and there was another button (maybe DOWN + X) to stop your momentum. It took me a good 2 minutes to pass the part where you had to fall onto 1x1 blocks. (This is probably just a skill issue though :) )
Overall, great entry. For 3 days of development, it feels polished, and when I finished, I was itching for more levels and content. The final stretch of wall bounces and jumps was very satisfying to execute.
Great job!