Nightfall opens as you, Noble 6, and Jun traverse a steep cliffside near a coastline to get into position above the Covenant forces. Once there, Jun takes a higher road to offer sniper support, while you hit the ground to deal with the enemy. It begins as a sneaking mission—the game uses this opportunity to introduce its new assassination mechanic—but it's not "mission failed" if you're seen. Besides, Spartans don't use silenced weapons like those pansies in the ODST program.

In true Halo fashion, the mission ebbs and flows between intense firefights and eerie calm, Covenant forces getting stronger and stronger with each successive encounter. This mission also introduces two new armor abilities that Noble 6 can utilize in combat: Active Camo and Hologram. If you've played the Reach beta, Active Camo is the same—you'll be cloaked as long as you stay still or move slowly, and it will jam nearby motion sensors. Hologram projects a duplicate Spartan, which will run toward your desired point drawing enemy attention and fire. The ruse won't work for too long—honestly, it's more useful in multiplayer, which is an awesome surprise.

Eventually, you and Jun come upon a pumping station being defended by some locals. After lending a hand, they reveal a cache of stolen weapons and you take your pick of the litter. Then, after defending the station from incoming attack—a few waves, Firefight-style—the militia takes you through a riverbed and you come upon an enemy pylon that must be destroyed. With the structure rigged to blow via remote detanotor, Noble 6 and Jun continue on and discover the true strength of the Covenant. In Jun's words: "That's no strike force, it's an invading army."

The next mission is Tip of the Spear, which we'll preview in the coming days. You can also read up on the game's space mission, which we saw at E3. If you want to read about the game's first mission, you can read Xav's X10 preview.

Halo: Reach will be released on September 14 on the Xbox 360.