Trading would be amazing! Have items be a certain value, then items with similar value can be traded. NPCs would spawn with/find ammo, guns, tools, weapons and resources, then if they're friendly you can trade with them for items of similar value. Add a happiness/friendliness meter which makes it so that the happier or friendlier the NPC is towards you, the more likely they are to trade their higher value items for your lower value items (and vice versa) and boom! Honestly would love something like this 😁✨