Thanks for playing, Glad you enjoyed.
After doing a little thinking im pretty sure the reason the file is so big is that most of the assets are actually 3d models. When i was making the game i wasnt really considering the size and if i wanted to improve the size it would be as simple as swapping out the 3d models for some 2d sprites. I understand the game becoming quite hard to look at and a new pallet would be a good idea, Thanks.