First of all, apologies for being late to the party on this one - it seems like everyone has already contributed their two cents to the subject of stories in games, so here is mine.

A fundamental difference between games and other story telling media is the introduction of choice. I cannot control what happens in the latest Terry Pratchett or Michael Bay blockbuster, and yet I am perfectly happy to sit back and enjoy the story that someone else has created. However put me in a protagonists shoes in a game and all I want to do is test the limits. A perfect example is my strong desire to shoot supporting characters. I want to know what happens when I shoot them, and yet I am always disappointed when they are seemingly bullet proof (although I do get a juvenile sense of satisfaction when it triggers a VO like 'ow, watch your fire!'). Of course if they died and left me in limbo without access to the next quest it would serve me right, but I wouldn't be happy. I want to shoot my annoying sidekick because I want something interesting to happen, not necessarily to suffer the consequences.

I digress, but the point is the perception is that stories in games are troublesome because the concept of a structured narrative is fundamentally at odds with the concept of choice. My character is supposed to be the good guy, and therefore the game rules are built around not letting me do things a good guy wouldn't do. If I kill the hostage then I start again, and again, until I save the hostage because that's what I am supposed to do. The perception is therefore that stories in games act as a restrictive force, preventing me from doing the silly things that I feel like doing or at the very least punishing me in some way when I do, all in the interests of 'the story'. In my opinion the two can co-exist with some compromises. If you could combine choice with a genuinely interesting branching storyline then I believe games would become the ultimate medium for storytelling. Perhaps one day our grandchildren will look back and say 'can you believe they used to have stories that only had one ending!'

One of my most memorable story moments recently in a game was during the first Modern Warfare. I'll warn you about Spoilers now, but if you haven't played this game yet you really should stop reading now and go grab a copy! Anyway that point when your character dies (I mean 'properly' dies) was a huge moment for me, but not for the reasons you might expect. Just for a fleeting moment I wondered if I had somehow done something 'wrong' that had resulted in his death. I instantly replayed the last level in my head, had I missed a bad guy that I should have killed? Could I have stopped this tragedy? The point is that I was engaged with the story and was relating it back to my actions. Then I talked to my buddies and found out it was just another scripted moment - I had not influenced the story afterall, I had just triggered it. Boring. 

I understand the limitations that prevent more games from having a branching storyline. Games these days are expensive enough to produce without having a whole set of levels or events that players might never see. Even when games do attempt this it is almost always signposted (press A to do the right thing, press B to do the wrong thing) which I personally feel reduces the sense of discovery. Games have definately started to move in the right direction to play on their strengths as the 'medium of choice' but until the stories can keep up our choices they will always be the glass ceiling that prevents me from killing my annoying sidekick. This may all change when games like Heavy Rain come along, with promises of consequences to our actions. Lets just hope those consequences are interesting.