Edit Sprites in "Creator Kit: RPG" possible?

Hello,

I found this interesting project, the Creator Kit: RPG, and I want to make a game based on this project but with a different theme, to be more specific: I want to change all the sprites in this project like trees, bushes, grass, dirt, etc to something like, metal rooms, metal floors, billboards, etc to simulate a space ship environment. Can this be done and how?

Thanks, Alex