Well thats the conundrum isn't it. How to ensure enough immersion without alienating others.
From the people I have tested the game on, the ones who can't get into it tend to be narrow-minded and take an objective view on everything. You know,
For some people a game is a game and that's all. A little program where you shoot bad guys and get a score at the end. You can't really teach these people how to get into a game because of some attitude or personal reason you wouldn't want to get in to. Perhaps they will go home and play it themselves when no one is looking but thats not worth investigating. All you can do is provide a small alternative for them to keep occupied and hope they cross over. For a few this was the light/dark conundrum. It was simple enough to provide a direct consequence if they had no imagination or were too anal to immerse themselves in a silly game. Similar to why a lot of people enjoy solving puzzles like crosswords-simply for the satisfaction of completion rather than the enjoyment of the words and shapes themselves.
The ones that have really suprised me are non-gamers who don't know what to expect and get skilled enough with the controls by the time they need them. Often the best response comes from female players ( I prefer the word interacters, but thats crap) but women tend to be a little aloof when it comes to letting their hair down and getting immersed in a game. Pardon my sexism. I think on both sides it's a confidence thing relating to accepting a style of play or connnection.
One aspect in amnesia that I have noticed and wanted to shed some praise on is the method in which it can whip typical action gamers into shape: breaking them into survival horror mode. Maybe it wasn't intentional (I am sure it was) but they would run through the first few levels without much care, neglecting the story trail and seeing the puzzles only as a barrier. However when they reach the water monster level this play style can't work and so they have conform to the intended playstyle regardless of them having not read the hints or suggestions left for them. This was perfect positioning as all they had really missed was a tutorial section and minimal backstory. Things that they would have to learn the hard way after being caught out by an early "correctional" sequence like the water monsters.
On the topic of implementing a voice for the player character, I feel that the incidents of speech or conversation must by in synch with the player would say or do. Random events like Daniel muttering break the connection because you don't expect them. It feels like a spoiler, that perhaps something is about to happen and although this is excellent if something does, it inevitably feels fake when nothing does.
He said something and nothing happened: it's just a game with some lines tacked on.
However, random elements that are not overly distracting (like human speech is) are fine because they form part of the atmosphere and not the narrative.
If you want simple people to relate with a character you have to make the character simple. If you want them to relate to a complex character and all it's complex processes, the player needs to be largely intelligent. This is difficult to make without insulting or dissuading a large majority of people/consumers.
If you wanted to appeal to everyone you would have to start with a base template that is adaptive to the initial progress of the player. Sort of like select easy/medium/hard mode but more sophisticated.
Once I am done with my stress testing I will write a proper report that may be of some relavance to you gentlemen as just now I am just dumping all my thoughts without much style.
P.S. Thomas you refer to the player as "she" an awful lot. Are you thinking of someone or is this perhaps a hint for future works.
P.P.S Immersion is much like when you are dreaming. It feels real but if there is too much reference to the real world you wake up.