The 12-hour countdown at Bungie.net finally hit zero this morning, revealing a teaser trailer for Halo 3's new campaign expansion. The short clip (embedded below) shows three metropolitan cities in ruins (the overlays on the video indicate the cities are Lumumba, Tanaga and Mbaraki). The video is interspersed with static transmissions -- a keen eye over at Joystiq pointed out a brief "01/06/09" flashing on the screen, possibly indicating the expansion's drop date.

No other details have been released about the expansion yet. We speculate that the expansion will also include co-op play as in the original Halo 3. The Xbox Live Marketplace description for the video states: "High action and deep mystery await players in this new Halo 3 campaign experience. Prepare to drop."

Video of the new trailer below:

Halo 3 - "Keep It Clean"

[via Joystiq]

Halo 3 Screens

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 1 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 2 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 3 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 4 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 5 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 6 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 7 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 8 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 9 of 226)

    This fall, Halo 3 explodes on Xbox 360, delivering a pulse pounding experience fans have come to expect from the critically acclaimed franchise. The all new single player adventure continues Master Chief's fight against the Flood and Covenant, while the multiplayer modes promise to suck away countless hours. (Screenshot 10 of 226)