Final Fantasy XIII is a single-player Japanese role-playing game and the thirteenth main entry in the Final Fantasy series. Combat uses a real-time variant of the series' Active Time Battle system, in which the player directs one lead character while the Paradigm system lets the party switch between combat roles such as attacker, healer, and support. Character growth is handled through the Crystarium, a grid-based progression system that unlocks abilities and stat bonuses. Set across the floating world of Cocoon and the wilderness of Gran Pulse, the game combines science fiction and fantasy elements with series staples like summoned creatures and airships. It was followed by two sequels, Final Fantasy XIII-2 and Lightning Returns: Final Fantasy XIII.