Game-play includes ground, water, and air combat with and without vehicles. The entire game is seamless with no levels to break up the experience. Like all Bungie games, we expect there to be an enthralling and entertaining plot. The Halo symbol seems to have a Marathon symbol built into it, so there may be some cross over plot elements. People have been crying for a 3D Marathon game ever since Quake hit the market.
In addition to the singe-player mode, Bungie has grand plans for multi-player Halo. Dynamix's Starsiege: Tribes proved that team play is the way to go. The people at Bungie have been playing a lot of Tribes and they took that message to heart. They plan on going even further. Not only must your team work together to win, when your team of jack-of-all-trades members sees a jeep manned by an accurate gunner, a skilled driver, and a vicious grenadier, you will begin specializing, or die. This is the first game we've seen that we think will give Tribes II a run for its money.
Tribes had the innovation of automatic voice commands. An overlooked feature of tribes was body motions that allow you to communicate with those near you. The body motions were overlooked because they did not provide enough information. Well, Halo went several steps further. Body motion is impressive and accurate. You don't have to type "Hey, look up at the hill by the jeep. There is a sniper there!" Instead, you wave your comrade over then point at where the sniper is. Good communication will take Halo's multi-player aspect even further into excellence.