I really would like there to be collectibles like the skulls in Halo 3 which encouraged you to go off the path of the game to find them. I liked them in Halo 3 because in some cases they were in bizarre places and involved you going of course or involved having to do things not normally done in the game to get them. Not saying I want skulls, just something along those lines and a reward when you collected them all would be nice too.