Pretty neat action-packed game! For the most part, it seems very similar to something like Super Crate Box except with the inclusion of bosses and a temperature mechanic, and with this it indeed delivers some great, explosive, juicy and slick action as you chaotically juggle all sorts of weaponry and dodge enemy attacks all while trying to keep yourself warm. Definitely enjoyed myself a bunch with this: it's simple but fun!
My initial impression wasn't that great as I felt like the heat mechanic wasn't that interesting as it was too easy to stay in the middle: felt like maybe there should be another mechanic to gather wood for the fire to keep it going, or for the fire to move. However, as the waves increase it gets more and more difficult to stay in the middle so it all works quite well: I guess it's just a bit of a slow burn and takes awhile to warm up, if you pardon the pun. Maybe it could stand to increase the difficulty quicker to get to the good stuff faster: feels like it takes until the 3rd wave for the game to actually start.
Still, I do have to admit that, in regards to the heat mechanic, I wish it was a bit more easy to tell. I actually died in the tutorial and had to do it again because I had no idea I was freezing: basically I think the effect of getting colder is a bit too subtle for its own good. Would probably help if the effect was a bit more amped up: maybe make the vignette larger or more dark blue as you get colder, use maybe some more ice related visuals like frost or cracks appearing on the screen, maybe some ice cracking or winter wind blowing sound effects, and so on. I also felt like the simple change in opacity and nothing else made it too difficult to tell how close you were to the limit: there's beeping but it covers too large of an interval, where sometimes I'd freeze not realizing I was that close to the end and thought I had more time. Maybe you tried to make it subtle so as to not impair the players vision, but I think you overdid it by not overdoing it. Oh, and I also wish it was more obvious when you get hit with something like a screenshake or a full screen red flash.