Thanks for your detailed reply! And great job in killing the cactus! :D The double damage due to missing I-Frames makes him way too hard.
With the balloon mask abilities, you can take the shortcut to the first room and reach and enter the final door there, unfortunately that's not really communicated. When falling off, you can reset with R, but of course we should prevent falling off in the first place. xD
Agree on the music part, we lacked the time for music and sfx. However, we intend to polish the game and add audio to upload a post jam version in a while. ^^
Thanks for playing, will check out your game as well!