Developer Bungie is including three Halo 3 multiplayer maps in a add-on disc shipping with the upcoming Halo 3: ODST.

The new Heretic map revisits Halo 2's Midship map, allowing players to plasma grenade each other all over the interior of the Pious Inquisitor. From purple reign we move on to the Forerunner Citadel, which features tight spaces where communication is key. Finally we make a stop off at Old Mombasa in the Longshore map, built for large scale battles over control of this strategically important port.

The maps and Halo 3: ODST will be out this September.

Thanks Casey for the tip!