Overall this game was pretty fun! It was a cute tower defense game and you did a great job of incorporating both themes.
The audio was fairly painful to listen to and I had to mute the game after about 10 seconds, some nicer bullet sounds would've made the game more enjoyable.
I also found it a bit frustrating that the polar bears spawned immediately, and I almost instantly lost the first level since I didn't know how to play and polar bears were already killing me.
The levels felt a little small for a tower defense game as well, I found myself just spamming shotguns as close to the entrance as possible just to speed the game up a bit.
You did an amazing job :D