if you mean to "unlock" them...no. You have to purchase and download those maps. They simply arent on the game disc and need to be installed on the hard drive.
You also could buy ODST, and that includes a second game disc that has everything Halo 3: Multiplayer on it.<-----thats they best deal, plus you get Halo: Reach multiplayer beta
There really isn't Halo 3 cheats except for manually done cheats from the controller itself. This cheat is a way of holding down your gun like master chief in one of the Halo 3 posters. If talking about like " type in this cheat and you unlock all the maps cheat" well no. There are no cheats like that for Halo 3. :)
Halo 3 has no cheat codes, but some people have modded maps.
There isn't a known cheat code for this on Halo 3.
yes and no. You can play all the maps in the halo 3, but you have to download the rest.
By getting halo 3 odst ( two discs ) first disc halo 3 odst campaign and 2nd disc halo 3 mythic comes with all the halo 3 maps.
No.
Yep i got them all, if you buy Halo 3 ODST you get them all including the other mythic maps
If by "halo 3 maps" you mean the Halo 3 Heroic, Legendary, Mythic and Cold Storage maps, then yes. However to play campaign levels, you must actually advance in the game to get to them.
halo 3 ODST will probably come with a second disc with all the Halo 3 Online maps on it (all 21) plus 3 more. will be halo 3 format.
nowhere because there are no cheat codes for halo 3
haw to make mode maps in halo 3
The Halo Odst Disk 2 comes with all maps (Plus 3 extra), and the ordinary halo 3 disk comes with no added map packs, so you don't have another 12 maps.