I’m fairly sure Kris asked the question in the Microsoft E3 podcast this week, as to whether Halo Anniversary would feature a mode to play the game displaying the original graphics.
Well, it certainly does. In fact, the game is running two engines at once; the original engine to retain the classic Halo gameplay, overlaid with the new graphics engine. The shiny graphics can be switched off at any time and you’ll enter “classic mode”.
The team at 343 have said that they will “never ignore the roots and foundation of what makes Halo successful”, and they’ll “never try to replicate what Bungie did.”
Source: Industry Gamers