Halo 3 Recon will be a new chapter in the Halo saga. which will tell the story leading up to the events in Halo 3. Few details have been revealed, but we do know that it will add hours of new gameplay and they'll be a multiplayer component.
Attendees at the show were also treated to Halo Wars, Ensemble Studio's Xbox 360 exclusive strategy game. The crowds were shown the campaign mode for the first time.
Halo Wars will debut in early 2009, but it's bad news for Halo 3 fans. You'll have to wait until late 2009 to get your hands on Bungie's expansion ("ooh er missus").