I feel like there needs to be more gravity-based games, as they seem to make the most interesting platforming challenges. The art style was appropriately spooky, and the game felt long enough, without overstaying its welcome.
The control scheme irked me a bit at the beginning, but I changed my mind by the final level. The introduction of the cannon that only shot right made me realize that the majority of the game's difficulty was learning an unintuitive way of moving, and by the time you got to the end, you should have gotten used to it enough to dodge a moving object in an open room. Adding the cannon at the end nicely combined a final test of the game's puzzle, with an entirely new one. Pretty Neat!
My only real complaint was that the random movement of the boss kinda detracts a bit from the puzzle-solving nature of the game, because some movements make the boss harder than others. I had trouble hitting him more than twice for most of my runs, and then he ate ten shot at once by slowly moving across the floor.
Nice Work!