Time travel, a television and movie trope, was the basis of Chrono Trigger when Square Enix released this new role playing game in 1995. Even though there was internal concern at Square Enix over this story mechanic, it is probably a large reason that Chrono Trigger was so well received by gamers. Instead of the usual storyline that we have seen time and time again, we get a unique take on the time travel theme. Chrono Trigger was one of THE reasons to own a Super Nintendo- Sega simply had nothing in their arsenal that could compare.
The world of Chrono Trigger consists of three eras. Prehistoric age features dinosaurs and humans sharing the Earth while the Middle Ages is all about knights, magic users, monsters etc. The Post-Apocalyptic era is less about humans (they are nearly extinct) and more about robots and other sentient creatures that are obviously not human. These eras are integral to the storyline of Chrono Trigger as you are tasked with visiting them all, including a fourth, and final era known as the “end of time”. In this fourth era you face Lavos, the creature that ended the world in 1999. You have to change that and stop Lavos.
What was truly interesting for me about Chrono Trigger was some of the stuff it pulled from other Square Enix games. The Active Time Battle system is the same as that which debuted in Final Fantasy IV. There was also team based attacks that would require more than one character to perform, and were devastating your opponent. Also, combat happened right there on the screen where you were exploring, no having to drop to another screen to do battle every few seconds. These were interesting additions to the genre, at least for me, and they helped solidify in my mind the place for Chrono Trigger.