Unlike previous games in the Battle Network series, the main focus of Mega Man Battle Network 4 is a tournament system where players will encounter a variety of cyber enemies that must be defeated. A new “Soul Unison” system is introduced for these two games. Duringthe game, some of the souls of those which have fought with Mega Man will “synch up” with his during battle. When this happens, Mega Man will be able to transform and use the special abilities of these souls during battle.

Players must be careful though, as there are forces of good and evil pulling at them throughout the game. In contrast to the “Soul Unison” system, there is a “Dark Soul” system in place. At times when Mega Man is in a pinch, a powerful and attractive “Dark Chip” will appear to tempt him. The more times these chips are used, Mega Man’s Net-Navi will become more affected by evil and consequences will occur, including the inability to perform vital “Soul Unisons.”