Halo 2 continues the story of the Master Chief, the genetically enhanced super-soldier who is the only human ever to successfully defy the Covenant—a coalition of alien races on a murderous march toward Earth. To the mysterious leaders of the Covenant, the human victory at the ancient ring structure known as Halo was an unacceptable failure. They will not fail again.
Halo 2 is powered by a completely new graphics engine designed specifically for the Xbox hardware. "Our code squeezes every drop of power out of the Xbox," said Chris Butcher, one of the sequel's engineering leads. "We're doing dynamic lighting and shadows, per-pixel everything, rendering gigantic, lush environments. The graphical features we're using are so advanced we don't even have buzzwords for them yet."
In addition to an epic single-player campaign, Halo 2 again makes use of the multiplayer split-screen System-Link feature and... Xbox Live.