Commentary Mode is a game mode that is the same as the normal mode, with two exceptions. The first exception is that someone will give commentary between each round, and sometimes during rounds. This will replace the written comments that already come between many rounds, but will generally say something different than the written comments do. This narrator will often be sarcastic, and will sometimes try to trick you into doing something that it wouldn't be good to do (or even into giving up). The other exception is that, after completing the main game on this mode, you will fight an additional boss. This boss is the Commentator Bloon, who you discover was doing the commentary all along.