Single-player:Be the hero. Take on the Covenant on your own and live firsthand the epic saga of the Master Chief. Wield dual weapons. Use previously undiscovered Covenant arms. Drive vehicles and pilot aircraft. Battle intelligent enemy A.I., and all-new alien pponents.Cooperative play:, Team up with a friend and save humankind together.Xbox Live multiplayer:, Improving upon the original Halo: Combat Evolved, Halo 2 is Xbox Live-enabled, allowing up to 16 gamers to play against people around the world., Halo 2 redefines the social experience of online gaming. New technology lets groups of friends stick together, find games, and meet new opponents., Players can split into multiple teams, form clans, or go head-to-head against new friends or old enemies., Players can personalize Covenant Elite or Human Spartan armor with custom colors and emblems to enhance battlefield recognition., Players can visit Bungie.net for additional game enhancements, including in-depth statistics and worldwide rankings.Improved A.I.:, Fight side by side with fellow human survivors who react quickly and naturally to events and circumstances; they help you when needed, man guns, and even drive vehicles for you. No two games seem the same, as enemy attackers coordinate, triangulate, and annihilate. They duck to take cover, clamber over obstacles, or smash their way through debris to reach you.Fully positional Dolby Digital 5.1 surround sound:, Duck as a rocket sizzles over your head. Take action as a Covenant Elite growls behind you. Every sound is fully positional, bringing the world of Halo 2 to an even more vivid level of realism.