oblivion is a good example - 400 hours in and i've never once finished the main story, and it's pure awesome.
star wars battlefront is another - countless hours and i'm far from sick of it, for the sequal they "listened to fans" and put a story in, and it made no difference, you played it once and forgot about it and then went back to doing battles, except they'd taken away the freedom to choose any soldier type and instead made you get a certain amount of kills before you could swap to jetpack man or whatever, thereby taking away the ability to play the entire conquest as jetpack man - bad move, obviously.
demon's souls is another - fantastic setting free from the inevitable cliches of a story and i love it. i hope they don't listen to those damn fans again for the sequel.
i would love to see game worlds developed with more of an emphasis on players creating their own stories - smaller stories that don't involve being the child of the prophecy or anything, more about factions, npcs, relationships, towns, and developing one way eliminates other avenues - rules you out from other factions, other relationships etc. this allows for far greater scope imo.
i'm fine with bioware going off on their tangent and making their stories, but i hate to hear about other developers following suit, i think it's a mistake, i think it narrows down the roleplay possibilities, greatly. i think games are the perfect medium for world design, for inventiveness, for player creativity, and i think they are very far from the perfect medium for storytelling - constantly having to ignore the fact that you are purely a killing machine committing bad guy genocide, for example.
so tell me, am i the only one who feels this way?