Finding health is a good suggestion. One of my plans was to add different power-ups and upgrades like faster bullets, element resistance, health upgrades, dashing effects, etc. Unfortunately I had run out of time to implement that kind of system. I originally planned for there to be ~30 rooms for the player to go through, but the lack of items had me reduce it to ~10 so it wouldn't be too difficult to survive.
The way the aiming works is that the mirror shoots relative to the direction it is in away from Clover. For example, if the mirror is directly above her, it'll shoot straight up. If directly below her, it'll shoot straight down. I could probably add a reticle or a line to show how the mirror shoots to make it more clear.
I'm glad you like the grass burning! That was one of my favorite mechanics as well. I get what you mean about not being familiar with the genre. I typically play and make platformers, so this submission overall was a challenge for me to design.
Thanks for your additional feedback! I tried your team's game as well and left feedback and it seems very promising so far!