I don't know exactly what it is, but I really liked this game. It's a little nostalgic for me as one of the first experiences with programming was with messing around with the qbasic gorillas game, which came with the code you could read and modify. This game reminds me of that game, but combines the classic shoot angle + power formula from games like gorilla with movement, multiple enemies, and turn based combat. I think the music fits the art style and theme perfectly, though it's a little soft at first (though thankfully you added a volume slider!). I was a little confused at first when the snowman noses hung in the air after they fire - but your own shots don't, so I'm not sure how to interpret that gameplay wise, but it did make for an interesting challenge.
Being from the early PC generation, I have a LOT of patience for keyboard only controls, but I think younger players might prefer mouse and keyboard controls, or at least an on-screen legend of the controls. I had to scroll down to the controls section of the description under the game a few times at first until I memorized the controls.
Overall, very good submission. I enjoyed it, and it brought back some good memories!