The seven main playable characters are Tidus, Yuna, Wakka, Kimahri, Lulu, Auron, and Rikku. Each of the characters levels up individually using a sphere grid. Instead of just leveling up your characters stats after a set number of battles, you gain spheres and ability points which are used to move around the sphere grid. The grid is made up of hundreds of interconnecting nodes which several branching paths for each character. Each node has a different effect, such as learning a new magical spell or increasing you attack strength. Battles are turn based, meaning each character (or monster) takes turns performing an action (like attacking a monster or using a potion). You can only use three of the seven characters in battle, but you can swap them out for any of the different characters mid-battle.