Lots of good stuff in the Metroidvania. The graphics, especially the backgrounds, are awesome and provide a great sense of place. I enjoyed the boss fights and collecting the new skills. Unfortunately, the ending glitched out for me and the slime king was just stuck in a daze.
My only major complaint is that I was fighting the controls quite a bit. When there are multiple mid-air maneuvers or near a wall, it felt like a bit of a crapshoot which one would come out. A few of the challenges felt like they were too precise for what the controls could reasonably expect (boss bat fight and a couple of the wall climb sections come to mind).
Overall great entry and it is quite impressive the amount of content you got into a jam game!