The game must be completed in a limited amount of time, seven days that can be extended to thirteen days. The NPCs are in constant movement, which means that depending on how much time has elapsed, they will be at different locations. Rather than using the Crystarium System from the previous games, the protagonist's skills improve as she completes quests, some of which are optional and are either obtained at the Canvas of Prayer or given by NPCs. Every day at 6, Lightning is taken back to the Ark, where she gives Eradia, an energy bestowed by NPC quests, to the Yggdrasil tree to extend her allotted time.