it helps describe what material you're making, or the light in the space which it is in.
^ I completely agree with this, I forgot to mention it, the hue will have to change for the object to better fit in the environment.
I'm not really convinced by your third wall though, it looks way too noisy for pixel art imho (plus it has 230 different colors).
EDIT: I just looked up NPA and discovered it means
not pixel art, so forget what I just wrote