There's the possibility to switch the graphics between old graphics and new graphics at the push of a button. Does that work for all games in the collection so halo 3 4 Halo 3 odst and halo reach?
No, only for Halo 1 and Halo 2.
Only works with Halo 2, I think it's one side of the control pad
With Halo 1 too
No, that only works with 1 and 2 Anniversary.
These are the only games that received a graphics update in the course of their anniversary. Hence the name of the two games.
With part one you can change while the game is running, with the two only via the menu.