5. Branching storylines and multiple endings
In Call of Duty games, the entire campaign structure has typically been entirely linear. Black Ops 2 will introduce branching storylines and choices through strike force levels, which allow you to choose the missions you want to go on.
You can get mission success or failure that actually plays into the story. If you fail, instead of getting a game over screen, the story goes on with a different branch. The mission carries forward with different branching stories depending on which missions you choose, as well as their outcomes.
