The basic concept of "SaGa Frontier" is based on its Free Scenario System, in which one can play as any of seven different protagonists, all of whom exist in the same setting, a solar system known as The Regions: a group of planets, each with its own culture, game-level of technology, and form of magic. The game is considered non-linear, in that from the beginning many of the characters are free to go almost anywhere and interact with almost anyone. Travel through most of the Regions is easy due to inter-regional ships traveling regularly between them. The player controls the protagonist on the field screen, a set of interconnecting pre-rendered backgrounds, and is able to speak with a slew of other characters in order to gather information, recruit party members, and initiate quests. Each character has his or her own storyline and a main quest to fulfill, but there are also several optional quests that any of the characters can participate in. Some of the main characters even encounter each other during their quests. The storyline of each character also changes depending on who is chosen, what is said in conversation, what events have already occurred, and who the protagonist has in his or her party, a concept first introduced in "Romancing SaGa 2".