I had a few ideas to resolve that, all of which would have required more work than I had time for during the jam. First, re-doing the pixel art to have consistent, stronger contrast between the floor and walls. Second, a shadow-cast effect with the wall tiles, likely using another shader. Third, layered tilemaps, so that walls do not have to use an entire tile and instead are overlayed above the floor tiles, to make the difference more defined. I’ll be testing all of these for later versions, alongside reducing the strength of some other visual effects, as together they can cause eye-strain.

I'm going to upload an update to "fix" the enemies soon.

I'm glad that you liked the movement mechanics. I was worried that the wall-bouncing might be annoying since it impedes moving through narrow passages at high speeds, which provides another incentive to go slower.

Fixed it, thanks for the tip.

Thanks for the feedback! I considered letting the player pass through enemies, but it eliminated most of the difficulty, so I decided to leave it in the game. What I should have also included is a way to restart when trapped (at low temperature, it takes forever for the enemies to kill the player). To try to balance the effect I adjusted the enemy tracking, so that they stop following after five seconds without line-of-sight. But, if backed into a corner, there is almost entirely no escape, except for the occasional physics glitch.  The best thing to do when pursued by many enemies is to slow down and let the temperature drop. Their tracking range decreases to 100px and their speed to 400px/sec when the temperature is zero, which is a little more than three tiles long and allows for out-running them.