You're facing the "interactive activity paradox". Yo want to have the player add some input in your game, but can't go far enough as to let him input anything, but merely what you have thought he would. Now the best solution, in my opinion, is to add the "backthought window" somewhere where it doesn't show too much, and leave it there forever, having the thoughts constantly show up. This will be a sort of internal dialogue, which can have any voice you choose, like in these film noir, where the main character is always talking about himself and his own feelings. This will help the player ease himself in the character's mood, and will help the designer design a game that will involve the player's feelings. If you can create a system that will react to a somewhat low level of input, and still get the player to actually FEEL, then you're a grand-master, dude...

Max Payne, being basically Film Noir in itself had internal narrative, where he would say very quotable phrases. My favourite being: "Einstien was right, time is relative. And when you are looking down the barrel of a gun, time slows right down, and if you want, you can live a whole lifetime in that second." I don't have the game on me now, so the specifics could be a bit off..

What matters, however, is them message it gets across - in this case an explanation for bullet-time. It can be used very well (Sin City), or very poorly (Farcry). In Farcry, the unimaginative protaganist, Jack Carver is asked whether or not he has the knowlege to fly a hang-glider. He replies with: "No, but I learn pretty fast when there arn't people shootin' at me!" This is a terrible character, as he tries to be badass and a toughguy, in a stealth game.

My advice is make the narrative intelligent. Make it suit the genre, if possible make it voiced out - it would be more effective to build up character and allows for accentuation and exclamation.

One more thing - I don't think that having a mental narrative destroys immersion, it becomes like an interactive film. It is no longer like Half-Life, where you are Gordon Freeman, who happens to be nobody (don't get me wrong I love the way Half-Life is told). The character becomes just that, a character and you can control him, but he still has a mind of his own.

Then what you're saying is you only want to be able to communicate what the character's body can feel through it's senses?

What exactly is the issue... it's not necessary to have the character say scripted sentences that could come in conflict with the user's own opinion. Look at all the games where the character doesn't say a word. Zelda with Link, Breath of Fire with Ryu... it works...

It's cool if you're looking for small details but I'm not sure what you were trying to achieve. I like it when main characters don't talk for you 'cause most of the time I find them stupid. Knowing what he feels through his senses is different and I like that. I think you should take it from that angle :)

Half-Life is one of the best games ever and throughout it Big Gordon doesn't say a word. Yet the other characters are so well developed and have such rich dialogue it doesn't really matter. I reccommend doing something more like this as it worked out really well for VALVe.

That is part of the point of Half-Life. Gordon is not really supposed to be a chracter, merely a medium under which the player can express themselves. Gordon is what we want to be. He is a geek (thoeretical physicist), though he likes a beer with his mates after work. When he needs to be strong however, he goes out and destroys several alien forces and most of the marine rangers basically singlehandedly.

I think that Half-Life does give us some guidelines of who Gordon is (and we can kid ourselves that we are too) - but it isn't too specific. You don't feel that Gordon isn't talking when you are playing the game, except for when Alyx says "you're a quiet kinda guy, aren't you?" Boy, did I want to kill her then.

Anyway, don't want to get into a half-life vs. anti-half-life flame war, as that would suck. Let us unite by agreeing that Jack Carver sucks.