In this first ViDoc created by acclaimed developer Bungie, Sgt. Buck, voiced by Nathan Fillion (Firefly), introduces his team of ODSTs and their mission into covenant occupied New Mombasa.

I didn’t know Fillion was involved with this project. Just another thing to get excited about I guess!

More Info from Bungie:

Gunnery Sergeant Eddie Buck has witnessed more war than any Marine should. He fought alongside Cole at Harvest—somehow managed to make it off of Reach alive. The fact that Buck is still on his feet says more about his mettle than his military dossier ever could. Now the Covenant have found Earth. Devastated her defenses. Anyone who could have stopped the invasion is dead or gone. But Buck and his squad of Orbital Drop Shock Troopers aren’t going to let Earth fall without a fight. These ODSTs may be headed feet first into hell, but they’re going to make damn sure it’s crowded with Covenant when they get there.