how do you get the mythic map from halo 3 without buying halo wars?

[Jerry]

there is maps like citadel,assembly,orbital,sandbox,longshore,and another one

 

[Apotheosis001]

wait for ODST to come with the entire map pack

 

[Ark]

you have to wait until bungie releases them which you will have to buy through xbox live

but there are only 3 maps. assembly, orbital, sandbox the rest will show up when Halo 3:ODST comes out in fall

 

[Little Moth]

You will be able to purchase and download the Mythic Map Pack from the Xbox Live Marketplace sometime around June for 800 Microsoft Points. It will contain the maps Sandbox, Assembly and Orbital. You can also wait for Halo 3:ODST to come out in Christmas 2009 which will contain the Heroic, Legendary and Mythic Map Pack as well as the 3 other maps you talk about which are Longshore, Citadel and Heretic.