ok i preorded halo 3 odst. i have halo 3 but i dont have any maps.. cus i rarely play it. but i heard that halo 3 odst is the same multiplayer but has all the maps? so does that mean you play on your halo 3 disc with the stuff on your harddrive? is the exact multiplayer? any additional info will be greatly appreciated.. ps only answer if you really know