The art is very good, don't get me wrong... but the games is already full of unused areas. I think it would be a smarter choice to add some characters and quests instead of more backgrounds.
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While I can see where you're coming from, the purpose of unused areas is to make it easier to introduce said quests and characters you're asking for. Adding too many characters and quests into a small handful of areas makes it feel like the developer isn't very invested in the world they're trying to create.