Looks pretty fun. I would like to suggest difficulty modes as well as a randomizer for items and abilities and enemies, and if possible for areas too. Randomizers add a ton of replayability to a game, just look at the fan made randomizer for Super Metroid and Metroid Prime, and the one built into Axiom Verge, as well as some other metroidvanias.

Will buy this on Steam the day it's released!