Stormonu
Legend
Right now, the only one I can think of is "Believable NPCs". That is, folks that the players can relate to in one way or another outside of a combat encounter or as a quest giver. Whether it's Blue Masey the barkeep who eagerly awaits to hear the character's travails when they come back from their adventures, or its Miss Trudy who tearfully says goodbye every time one of the PCs leaves, fearing they will never return - having NPCs who the players enjoy interacting with time and again helps to draw players into the worlds as more than just a game.