The game definitely has some promise, but it seems a struggle to get through.
While the furnace has a bar showing how charged it is, nothing else has similar bars for the health. I think maybe I eventually realized the pylons change color, but everything is in the warm color scale that I'm still not entirely sure. Though I think maybe the powering down sounds were from the pylons?
The spiders seem to spawn a little too fast as usually just as I've managed to kill one, another spawns. If they're both on the same side, then I get some time to charge the furnace, but if they keep alternating, then I don't get a chance and am usually just getting to the furnace or almost there when another spawns... somewhere. There's no signifier I can see to which side the spiders are on. I at least had sound on to know they were spawning, but unless I was supposed to have stereo sound, which I don't, I have to guess which side the spiders have appeared at.
Then the furnace itself, while it looks nice, the design doesn't help the game. You seem to need to be at the port where you plug the light in to place it and pick it up, and that is at the right side. While the furnace itself is in the middle of the two pylons, since the port itself is on one side, it means it is closer to the right pylon. Because of this, if the spiders spawn more on the left side, it ends up harder to charge while if they spawn more on the right side, it's much easier. Of course, if they only spawn on one side, you can kill them a little faster if you're already there, but it still hurts your movement time.
Plus it seemed that even when hurting the spiders, they were still able to attack the pylons, so it ends up feeling less like you're stopping the attack but more just slowing it down, which if the spiders are alternating areas, even if you are not letting yourself get hit and are killing the spiders as fast as possible, you can still lose even when you're at the pylon killing the spider because it can break while you're right there.