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.