I'm not sure what you mean by 'graphics engine'. Halo 3, and any game on the Xbox 360, uses a special version of DirectX to send data through he pipeline into the card for a bunch of things that lead up to rasterization. The term [i]rendering engine[/i] is more often used to describe what you are talking about. For instance, the Halo 3 rendering engine has all these great features (object bump mapping, HDR lighting, multipass rendering) but that is specific to the game and is built upon a graphics engine, in this case some version of DirectX. Another example: Halo 3 might do the bump mapping in a vertex shader, but in this case you mean to refer to the bump-mapping feature of Halo 3's rendering engine instead or programmable pipeline (in this case a vertex shader) support in the graphics engine. So that should clear up our terminology. I do think Halo: Reach will have completely new game engine, not just rendering. Halo 3: ODST is merely (and I hate to say merely, 'cause it's freaking awesome) a campaign expansion of Halo 3, and uses the Halo 3 engine. Halo: Reach is an entirely new and ambitious Halo Game, and for them not to write a new game engine would break every pattern of game development they've every had. In fact, Halo 3: ODST might be the first Bungie game not to have a new game engine.