Hey, thanks for the huge comment!
1. More levels are coming and I'm focusing on levels like the elevator one. I completely agree that the elevator level is awesome, and I've got a few interesting things in the works (that are turning out to be harder to make then expected, but they'll be ready eventually!)
2. Kill zones on the elevator is probably a good call, though the gem thing is actually intentional. I think it feels better to just keep the game moving, rather than force a restart when a gem is lost.
3. A colourblind mode is another good idea, it could perhaps use a consistent, high contrast colour scheme.
4. That anim is a bit of a relic from the jam release, though it was intentional to make it clear what hit you (things fly by so quickly, I didn't want it to seem like you died out of nowhere). It could be a lot more snappy tho, I'll work on it.
5. Finishing this game is my goal, tho 'masterpiece' is a bit of a strong word.
I've got an update coming in a few days, I'll see if I can address some of these things before then (tho I don't have much time, no promises). Thanks again for your feedback and support!