Chrono Trigger

Chrono Trigger begins with the 1000 A.D. Millennial Fair, where Crono and Marle sample Lucca's new teleportation device. Marle volunteers, but disappears through a strange portal when the machine reacts with her pendant. Crono asks to be sent through the machine to find her, and discovers he's traveled back 400 years. He meets Marle at Guardia Castle, and learns that a search party looking for the missing queen of that era found her instead. Marle then vanishes; Lucca arrives and claims that she's actually the princess of Guardia in 1000 A.D., and that since her ancestor was not rescued, Marle ceased to exist. With the help of a talking amphibian called Frog, Crono and Lucca rescue the real Queen, kidnapped by "Mystics" who worship the wizard Magus. Marle reappears and the group returns to 1000 A.D., where Crono is placed on trial for allegedly kidnapping Marle. He's sentenced to death, but breaks free from the prison. With Marle and Lucca, he flees the king, to nearby Guardia Forest, where they stumble into a time gate. They're shocked to find a devastated world filled with futuristic ruins (later determined to be 2300 A.D.), and uncover a video of the "Day of Lavos". The video shows a creature called Lavos erupting from the planet's surface in 1999 A.D and decimating the planet. The group resolve to prevent this catastrophe and recruit a robot named Robo before entering a new gate to arrive at the ethereal End of Time