Hello. I'm new to Unity and I don't know what to use to make art for my 2D game that has still images and animations. 1. What format should my arts assets be in? A sprite sheet? Separate images? 2. What external tools are good for making art in the required formats (sprite sheets) and files? In my previous game with a different engine, I used vector graphics so that I didn't have to worry about the size of the image, just the proportions. So I'm lost when it comes to non-vector graphics.