Omg such a detailed review! Thanks so much! This is a dev for the game btw :P Really cool to see people enjoy the game like this. Here's my response to your questions:
1. I guess we really liked how controlling where you want the light felt like part of figuring out each puzzle. We were considering having a mode where you just directly control the firefly with your movement keys, but we liked the depth added by trying to figure out how to position yourself in the correct way. Also, moving the firefly is very powerful, so we specifically didn't want that to be something you could do immediately. Instead, you have to figure it out, which also gives the player a little "Aha!" moment as they figure out how it works.
Although you may be right, it's possible it didn't add anything meaningful to the experience, and would've been better to streamline it, that's just what we were thinking AS we were designing it, many of those things turned out not to be true as we playtested :P
2. Huh, that's an interesting point. That was a very last minute addition. Originally the checkpoints were invisible (think of how hollow knights respawning works) but then we realized it would be better if they were visible, so we added a graphic for them. We really couldn't think of anything so I just threw that sprite together. Just the qualms of a 4 day game jam I suppose
3. So we really wanted to give a sense of isolation in this game. Since it's a puzzle game, we saw value in the player figuring out the mechanic themselves, hence why we don't have a direct tutorial there. If you're playing an old version of the game. there's not even a sign that says "Lock (hold) X/L/Shift". That wasn't a specific design choice, we just accidentally deleted that sign right before submitting and didnt notice until it was too late. Oops!
But the area where you fall is designed to be open enough so you can figure it out on your own, with subtle guidance by the sign. We found through playtesting that it wasn't very clear where you had to go, which was definitely a lapse in level design on our part.
But the design philosophy of that area was 1) they fall down 2) they see the sign by walking up to it 3) By messing around they learn they can screenwrap, and from there they figure out to go to the checkpoint.
So yeah, we did want a certain level of confusion there as they figure it out. Perhaps it was a bit too much tho