There is a genre that I really can't stand playing, not because the games are dead boring or of generally bad quality, but because they feel too real to me as a player. It's the horror game genre with games such as the classic Resident Evils and Silent Hills. I mean those games apparently are amazing masterpieces, from what I hear, but I never can get my nerves together for long enough to finish one of them. In fact, I usually quit the game after the second scary moment in a game. In Silent Hill 2 I stopped the game before even getting to the town. That whole eerie fog and the sounds scared the living hell out of me. Funny though that I find most of the supposedly scary horror movies (Grudge, Ring, both jap. versions and etc) really just entertaining, and not that scary at all. I can't help but laugh out loud sometimes even when a particular cheap trick is used in a particular cheap way. So...what is it with those freaking games?
I think it's obvious. First of all, I play the protagonist, that means that I personally am Jill Valentine, Harry Mason and etc. When those screeching sounds coming from that dark corner, it is really giving me the creeps. When a freaking 4 legged monster frantically moves toward James Sunderland, it is me who panics and is feeling helpless swinging around a piece of wood with a nail on it. Horror games have in my opinion found a perfect way of connecting the protagonist with the player, really making the player a part of the fiction, creating a real sense of experience. It is my adrenaline shooting up, it is me feeling unwell inside, not just the character I'm controlling. I don't have to root for the hero, because I wouldn't have to make a conscious decision in life to root for myself either. It's that strong a connection.
Which brings me to other games that have weaker connections. Those would be in my opinion pretty much all RPG's, Adventures and Action games. Designers often have a real hard piece of work to create that connection. RPG's kind of try to sidestep the issue by letting you choose how you play and how you develop the character. FPS's often don't even require much of a personality for the protagonist, because you're not looking at him/her most of the time anyhow. Half-Life for example makes a point of breaking that illusion (you are Gordon Freeman) as little as possible, by not including cut-scenes, there being hardly any mirrors at all and everybody looking at you when they talk, and Freeman himself never speaking a single line of dialog.
More interesting are Adventure games and 3rd person action games. Everybody knows that Monkey Island has a lovable protagonist in Guybrush, just because he's such a likable and funny anti-hero, and yes, identifiable for a broad range of gamers (but not all). And he better damn well be, because in those story heavy sort of games, if the player doesn't even really like the hero, then there's no incentive to play at all (except for puzzle enthusiasts maybe).
Same goes for games like Tomb Raider, Batman Arkham Asylum, Mafia 2 etc, but to a lesser degree. Those games are more action intense, meaning that you will have bad guys attacking you, so it is a natural thing to fight back and not ask yourself first "Well...do I really want Lara to succeed?". Those games still have you watch cut-scenes to show you more of the protagonist and their personality. So it's a bit 50 - 50 here. Even if I don't really like Solid Snake, that doesn't really matter when shooting/strangling/blowing up bad guys. I can still have good fun.
What I'm really getting at is that horror games are a special case that has an advantage over other genres. They speak to very basic human emotions: fear, confusion, panic or loneliness. Everybody knows those feelings and in the gameplay mechanics of killing stuff and running around creepy empty places those emotions can be evoked really effectively. Many other games have the main character go through much more complex feelings (not to say that horror games don't feature deeper emotions for their characters), such as shame and revengefulness. It is a lot harder to communicate these emotions to the player. Most of the time these things are only shown. We only watch Kerrigan getting abandoned. If we can feel compassion for her (for that reason she is pictured as an attractive woman), we can root for her or at least understand why she's so pissed off. But we don't really feel revengeful ourselves.
What this wonderful medium of games allows us to experience is not just the ability to act and change the outcome of events, but also to feel emotions tied to our own actions and things done to us as a direct consequence. Think about this: if you get beat by another player in SC2 in a particular humiliating way, you will likely feel real anger, real frustration and a real desire to get your revenge. (Maybe not as strongly as the guy below playing Halo is angry with his team mates)
It isn't even really about the fact that your opponent is a human and not an AI. If it was an AI, we'd still feel those emotions. Having a human being to be frustrated with makes it only more personal. We actually feel so pissed off because we simply screwed up. Our actions led to a horrible defeat and that's why the defeat tastes all the bitterer.
What game designers need to figure out to really engage a player and create that connect isn't really about creating protagonists with amazing personalities. Gordon Freeman could be a walking piece of wood for all I care. Gameplay should feature direct consequence for the huge array of interaction we have in real life that therefore must also be featured. No more cut-scenes. No more walls of text that tell us how XYZ feels about this situation. That's the reason why Warren Spector's motto "Playstyle Matters" is so darn important to understand if the medium is to advance and to take full advantage of interactivity.
My personal view is that in order to make that move forward, breakthroughs in AI technology must be made, as well as in Input technology. Maybe the Wii and Kinect are the right steps forward in that direction, and not just the entry door for new casual gamers.