slick concept! great simple little game! I enjoyed the handwritten controls text--it was a nice touch.
shift and control both feel pretty questionable in terms of player agency. why would I ever stop holding shift? it only improves my performance. is the small utility in being able to adjust your controller height (unclear if this is from the bottom up or top down, which might have some kind of bhop potential) worth adding a whole extra key--left control--for the player to think about? if you raise the skill ceiling and make the movement system micro in a way that makes these inputs matter, this could be a deep and rewarding experience. on the other hand, you might want to delete them entirely.
one minor point: it's sort of unclear to me what triggers a 'lose' scenario. it might make more sense to just trigger this on contact with the bottom of the well, to improve readability. and/or add a reset key. every so often I get a bad spawn that I'd prefer to redo.
great work!