Hi! Sorry for the delay.
Basically you can either use a combination of sprite + background OR a CG for the game. Not both things, if that makes sense? (Let me know if it doesn't).
So for the game the image assets can either be:
1 Sprite and 1 BG OR 1 CG
But not:
1 Sprite, 1 BG, and 1 CG?
That’s correct!