Which Final Fantasy game first used the Active Time Battle system?

Final Fantasy IV was the first Final Fantasy game to use the Active Time Battle system.

Active Time Battle, usually abbreviated ATB, replaced strictly alternating turns with continuously filling time gauges. Each character and enemy effectively had an internal clock influenced by speed, so combat could progress while the player selected commands. This introduced urgency and made battles feel more dynamic without abandoning menu-based role-playing mechanics.

The system was designed by Hiroyuki Ito, with development contributions from Kazuhiko Aoki and Akihiko Matsui. Ito reportedly drew inspiration from watching Formula One racing, where vehicles move at different speeds and overtake one another. Final Fantasy IV introduced the system in 1991 and helped establish a combat format that became strongly associated with the series.

Final Fantasy V refined the idea by displaying a visible ATB gauge, while later games added variations such as Active and Wait modes. Final Fantasy X temporarily replaced ATB with Conditional Turn-Based Battle, but Final Fantasy X-2 brought ATB back. The other listed games—Final Fantasy III, V, and VI—therefore came before or after its initial introduction rather than originating the system.