"make a 3d game only using flat images. no meshes."
Would this mean that I wouldn't be able to model out a world / level? or does this mean that all of the objects and other models would be MS paint stuff?

Sorry, I didn't realize it would be a pain to do that until right now, haha. Go ahead and model stuff like the world and level, but make sure the textures are all made in paint, haha.