Great puzzle game, The thermoluminescence was a great and accurate way to show temperature as well as the fact that temperature reached equilibrium, the theme was on-point. The level design was also good but I have to agree with other comments that some levels needed too much repetiton, maybe if the effect was more dramatic it would be better, once you solve a puzzle executing it should be as painless as possible unless difficult execution is part of the puzzle and game like some puzzle-platformer but this wasn't the case.
another nitpick is that jumping is too unforgiving, you should give a "grace period" when falling from ledges to jump, this is not noticed by most players but feels a lot better, as well as being able to input jumps a bit early from the landing. This is a puzzler not a platformer, but failing the last jump in the level with the hot column and water to the right was really frustrating.