The trailer reintroduces us to Master Chief and Cortana (sort of, long story) as they reflect on how they would live differently if they knew how they'd die.

The reflection doesn't last too long, as Master Chief quickly gets to killing plenty of Banished, the new splinter faction of familiar Covenant races, shooting Brutes, Grunts, and running over Jackals.

We also see Master Chief encounter a strange female alien/robot/AI hybrid character who warns the Spartan that "you are not the future" before attacking.