To start: I believe NPC's make an important mark on a game, weather it be a fantasy or a FPS. They are essential to the flair and flavor of the game.
They are the ones that support game support in a way and bring together a game altogether.
Next: Quests: Quests are essential in any game, i think that certain FPS's forget that except in story mode.
Next: Rewards: Rewards are the essence of the risk. This could be anything as simple as a key to a chest that you may come about in your journeys (FPS: weapons/item crates), or as major as a new gun that you don't have to purchase.
Next: Character Progression: The only reason to have your own individual character is to try to make it yours, and as unique or necessary as possible. This is done even in most FPS's. Games from Call of Duty even use this method somewhat. Skills/Abilities/New Available Technology.
I hope as many people as can will post or also request these features, even if it is later that they happen.
