"really well described" in the 2001 novel Halo: The Fall of Reach.
Franchise boss Frank O'Connor says it's a "device to keep the player invested" playing as the hero, which would diminish if we 'see him'. These are "gamey elements" unique to our industry.
Any proud Halo nerd worth anything could probably describe Master Chief's physical appearance rather well, but Bungie and 343 won't cross that final line it seems.
At the end of Halo: Combat Evolved he does in fact remove his helmet but the camera pans away. "It's funny we don't then show his face," said Halo franchise development director, Frank O'Connor. "But that's a device to keep the player invested in the character and keep the player from constantly being reminded that they're not a hero or that they have to be a boy or they have to be a girl, or whatever that is."
O'Connor noted Valve's Half-Life star Gordon Freeman as an "extreme" to this kind of philosophy. While fans can easily recognise Freeman and have access to his physical appearance, the protagonist doesn't say a peep - ever. "The flip side there is his face is on the box. So everyone knows what that character looks like and they can draw Gordon Freeman perfectly well. You can't really do that with Master Chief."
"These are gamey elements, and you don't have these discussions about movie characters necessarily, and it doesn't matter with books because people fill in the blanks," he continued.
Would 343 Industries ever gamble with the Halo franchise and kill Master Chief?
"That's a conversation I can't get into," O'Connor said. "I'll say that in Halo 4, things happen. Previously we've been scared to commit to difficult paths in our game, but good interesting stories have things that happen in them that are not comfortable and that are meaningful and that are permanent."
"I'm not trying to hint at something other than our general philosophy and the shift in the attitude we're taking about storytelling. We can make the story matter more to people by doing things that matter. That's not rocket science."
"Luckily we have a publisher and owner that allows us that freedom and they trust us to make the right decisions with the fiction and the universe." Halo 4 releases on Xbox 360 November 6th.