That rather takes the urgency and drama out of a game, doesn't it? A storyline has to have some element of "bad things are happening" to make it interesting. If you mean those plots have been overused, granted that's true. But a rescue-the-princess, slay-the-dragon paradigm is just structure, really. I'd think the game needs a simple plot to get things moving.
Once moving, if the game is any good (dialogue, atmosphere, combat) all that stuff will bring it to life.
A lot of good ideas here. Some more I thought of reading this:
-Be able to name your character! Nothing's more of a letdown than opening a game and reading "You're Jack Studley, blah blah blah"... hey, let ME decide who my character is, what sex, temperment, all that.
-Combat needs to be unrealistic. Yup, it sucks to get killed by a single bullet, or backstab. Let my character tough out several shotgun blasts to the chest, patch himself up with a handy doctor's bag, and keep truckin. (This doesn't count critical hits... those are conversely essential).
-A lot of games (console mostly) boast of massively interactive environments, where you can open every box, tip over every chair and so on. Bah! Who needs it. Spend the dev time on story and entertaining the gamer, and that's time better spent. I don't buy games to knock over furniture.
-Keep the mood of the game "mature." Fallout and Torment are terrific examples of a mature universe. I need to know if I screw up in the game world there will be bonafide consequences I won't like, and I'm not just talking Combat. Additionally, that gives players the opportunity to explore the dark side if they choose. Nothing's worse than a game where everything's super-OK!, which includes most console games.
-A new universe to explore! Western, private eye.. How about a SPY story! Choose which of several nations to be from, some ultimate prize all are after, how to get at it. Be a lusty Mata Hari, a suave undercover, the brutal thug, a shifty sniper behind the scenes type...
-Oh, definitly isometric, IMO