The concept for Final Fantasy XIII's battle system is to maintain the strategic nature of command -based battles, while also including the excitement and speed found in fast-paced battles. This system stemmed from a desire to create battles of the type found in Final Fantasy VII: Advent Children, while adding multiple player characters to the battle. Like Final Fantasy XII, the battles will be in real time, without any random battles.
Active Time Battle makes a return in Final Fantasy XIII but works completely different to how it did in the previous games that used it. In keeping with command-based battles, players input commands by selection through a reel on the bottom-left hand side of the screen. Each command has an ATB cost, which reduces the total ATB bar. Selected commands are placed on a row of upcoming moves, above the bar. As characters fight, each command is used in turn, with the current command in use turning yellow. Commands can be chained together for certain effects. The environment also plays a role in battle; for instance, Lightning has been seen sending a soldier into a light, electrocuting him and multiplying the damage.
A map is seen in the upper left hand corner of the battle screen, with blue dots representing allies and red dots signifying enemies. The dots emitting circles are the characters currently affected by the fighting.
The upper right-hand corner of the battle screen shows a circular-shaped gauge, representing the Overclock mode. When full, Overclocking allows the player to induce a slow-motion effect, almost pausing time for everything other than the player. Once Overclock is activated, a rapidly decreasing number appears inside the circular gauge, signifying the duration of the Overclock status. This system may replace the traditional Limit Break system found in previous Final Fantasy games.
Final Fantasy X battle director Toshiro Tsuchida will return as the battle system director for the game. He has the intent of giving individual enemies their own personalities and background stories. He also replied with "no comment" when asked if players will be inputting commands for ally characters, or if they'll just be in control of a single character.