Gordon Freeman’s neutrality of dialogue and lack of overt personality within the game do not make him a non-character, but are in fact his strength. His lack of preconcieved identity provides not a single barrier with which to distance him from the player’s own personality, making him a blank canvas on which they can imprint their own values and outlook. Valve have even made it impossible for the player to ever see Gordon from a third-person perspective, either through cut-scene or reflection, meaning that in no instance does the effect of seeing a character who does not look like themselves pull the player out of the experience of ‘being’ him.
This higher level of scrutiny is similar, it seems to me, to what many transgendered people experience, when they're held to a different standard of masculinity or femininity than, for lack of a better term, "cissexual" men and women. One might attempt to deny a transsexual woman her femaleness, for instance, by saying, "He's not really female, he likes video games too much," but wouldn't dream of applying this same logic to those cissexual women who love video games.
Who would have guessed that when you remove Garfield from the Garfield comic strips, the result is an even better comic about schizophrenia, bipolor disorder, and the empty desperation of modern life? Friends, meet Jon Arbuckle. Let’s laugh and learn with him on a journey deep into the tortured mind of an isolated young everyman as he fights a losing battle against lonliness in a quiet American suburb.