I was pretty happy with this game once I got to the end of it. I think a lot of the exploration and some of the combat systems ended up working pretty well.
I think it is worthwhile to describe a couple of the things I liked, and the things I didn't like.
I like the gamepad controls, they're what I used for the most part. I was sad that the joystick didn't work.
I never really understood what caused the hearts to spawn. It seemed like I would just have to wander in the yellow area for a while before the game decided to spawn the heart. This became especially confusing when I couldn't figure out what I needed to do to get past the beige walls. I think making the hearts visible at all times would be a better idea--I don't think it would hurt the gameplay, as the map is large enough that even very easy-to-spot things can be difficult to find.
I think the game is too long for it to erase all your progress when you lose. At one point I had to leave for a bit after playing for about half an hour; thankfully I wasn't killed, but had I died at that point, I don't think I would want to re-do the last half hour of gameplay. So the game should really keep all the upgrades, hearts, and levers that you've found after you die.
On that note, the game ended up taking me about an hour. I don't think this is really too long, as at least half of that I was having a good time. However, at times the sheer size of the map seemed a little much--in particular when looking for the third lever behind the fire blocks behind the beige wall. I think a little bit of tedium in exploration is good, but there might be just a little too much wandering around.
As other people have suggested, the other solution to this would be to make a minimap. One interesting idea could be to have everything but the hearts displayed on the minimap.
At first, I thought that the combat system seemed to fall flat because combat was very difficult--death was essentially guaranteed. However, I ended up thinking the combat system is very good. Before you get the fire upgrade, the combat is more or less impossible without dying, in my opinion, meaning that avoiding enemies is the way to play. However, combat becomes viable after you get the fire upgrade, and so the player's relationship to the enemy changes significantly even though the enemies haven't changed in behavior at all. I think this is pretty neat.
I also liked the variety of things that the player needed to find. Having to activate levers and find the fire upgrade--they were both very welcome variations in what I was looking for. I think maybe having a starting area with a lever that you have to find would help put me in this mindset earlier. That is, at first I wasn't aware that the game consisted of more than avoiding enemies and following the radar--the game started to feel much more alive once I was aware that there were more things in the world than just enemies and hearts.
I find the graphics to be pretty nice. I would have liked a better indication of how many levers each beige door took--the first lever I flipped seemed like it didn't do anything because the two doors I had seen thus far had not moved.
The tiles graphics give me this sort of Diablo vibe, maybe? I think they're pretty good.
I also like the repeated use of the gradient orb idea. It kind of reminds me of retro games that would have repeated use of palette-swapped sprites.
The end screen is very charming as well.
Overall I had a good time playing this game. I hope that some of my feedback is helpful somehow! 😅