theres a lot i can imagine being easy to do in game by adding interaction points and items.
I see interaction points as just entities that sit on a tile and optionally have a sprite attached, items are flags that can be added to a player and can be treated as keys for interactions (possibly with optional sprites to be displayed over the top of a player)
so, an interaction point drawn as a face can ask you to bring them a fish, an invisible interaction point can be sitting over a body of water that gives you a fish if you have a rod, another character interaction point can flag you with a fishingrod if you have a coin, a third can flag you with a coin if you are holding 3 plates and 3 can be plates sitting on tables in the local restaurant.
i know that is a bit of a ramble but it feels like two additions that can mean a lot of freedom to add story and tasks. these interaction points could even also be signs as well as npcs and possibly doors if you add options to toggle sprite visibility/tangibility etc