I played to the end and enjoyed this game -- nice work!  The visuals and atmosphere are great, and I liked the music and thought it fit the vibe well (did you write/create it?).  The pacing of the difficulty of challenges was well done, the level of challenge was nice, and the concept of jump-only movement in this way wasn't something I'd seen before.  Not having lateral movement when grounded took some getting used to, but not in a bad way -- over time I developed the strategy behind the different ways to move through the space, and I appreciate that it's something different.  

Fwiw, the game did not play for me on Mac/Firefox (the opening text rolled out at about 4 characters per second, which meant it took several minutes to end, and then none of the keyboard inputs worked once the game began).  It worked well on Mac/Safari.  I was a little unsure if I'd completed the game when it ended, and I then ended up falling out of the gameplay area by checking if there were additional rooms to the right or left -- the top edges could use colliders and/or an indication that the game was over.  But those are minor issues in an otherwise strong game --  nice!