Final Fantasy XI Online is the franchise's first MMORPG as well as the eleventh installment in the main series. FFXI was the world's first cross-console MMORPG, available for Windows, PlayStation 2, Xbox 360 and Steam. Since its release in 2002, it has become the most financially successful title in the Final Fantasy series. Due to the nature of online RPGs, FFXI differs in that the player is not the only hero. Instead, each player creates a customizable character and adventures through the world of Vana'diel with other players; leveling up, exploring, completing missions, quests, and much more. Leveling up requires a group of people working together in what is called a Party, with each participant contributing their own skills to help take down a foe and gain Experience points. Battles occur in real-time, taking the ATB system to a new level, which was emulated again to a certain extent in Final Fantasy XII.