Wow, this was incredibly impressive! The simple pixel art looks great, and the level design flows quite well, especially considering that it is procedurally generated! I did run into a number of game-locking bugs such as exiting a room into a room without an entrance for the character to show up in, and accidentally jumping out of the world into a bottomless pit. But I am sure these issues can be polished out with time. While I generally liked the progression gating based on attacking types of blocks, it did make for a bit of a linear experience. I would love to see more types of ability upgrades and a more branching path structure in the future. But overall, this is an excellent proof of concept. Great work!