You know when you feel in the back of your head that you're forgetting something but can't quite place what it is? Up to the last hour of the jam, for me it was the mute button. I guess I'll add basic options post-jam.
Regarding the elevator thingies, that's something I followed very strictly from the original, without realizing how harmless those enemies look. In Cybernoid, anything that moves is an enemy. But here these things do look harmless on first sight, I guess I should add spikes to them or something.
I'll try to get more people to play the game and re-evaluate the placement of checkpoints if many of them have trouble with the first couple screens. Thank you very much for the detailed feedback!!