This was an amazing start for gamedev! Considering you only had 8 hours to make the game, I wouldn't complain too much about the lack of audio, but I liked the art! It's nice and simple. I really liked the effect the snowballs leave behind when you hit a snowgre, it feels like a satisfying explosion. I have a few things you can try to add in for later to improve the game, I'm not going to mention the obvious things you probably plan to add later on though (ie. main menu, audio, animations)
-If you were to add a main menu, maybe some button animations that make it feel nice and satisfying to just hover you mouse over. Things like that would make interacting with UI way nicer to do.
-WASD movement would be nice too, I'm not used to using arrow keys to move so it felt a little weird at first, especially since your right hand is on your mouse and not the hand that's using the arrow keys.
-Being able to hold down the mouse button to keep throwing snowballs would've been good too, with a good throwing SFX, it would be very satisfying to just throw a snowball.
Overall, amazing start to gamedev! I'm surprised you were ale to get this much art into the game along with the gameplay in just 8 hours, impressive!