Thanks for the comment Haunted! I'm sorry you had a rough experience, the flamethrower issue is probably a systems requirement issue, had a number of people test on different PC's but unfortunately can't ensure requirements for a project at this scale.
To address the big one, the temperature drops when enemies are around, multiplicatively. If there are more enemies, the temperature drops more quickly. You can heat up very quickly with the flamethrower, just watch not to get too hot :). Definitely think the game could have used a more formal tutorial, going to outline some key mechanics in the description to help future players.
Definitely interested to hear what was going on with the flamethrower, if you were having bad lag spikes it may have been interfering with collision which is very unfortunate. Thanks again for playing!