The Time Gate is a powerful device found on the Planet Styx. Originally seen in the first Star Ocean, it was initially thought to only be capable of time travel, but later research showed its real purpose. It is fully sentient and only allows those it deems worthy use its powers.
Since the party had no way of reaching Asmodeus to make the serum to the Lezonian bio-weapon in their current era since he was killed three-hundred years ago, Ronyx suggests going to the Planet Styx to use the Time Gate. This decision was made even though the Gate was in restricted space, and its access could result in Ronyx becoming court martialed. Seeing no other option, the group decided to go.
On Planet Styx, the Time Gate hears Ronyx's request and allows them to travel to Roak three-hundred years ago. Ronyx tells the party to leave behind their equipment, and jumps through, followed by Millie. After Ilia trips on the steps, Roddick helps her up, but due to this moment of pause, the Time Gate sends them to a different area of the past than Ronyx and Millie.
Ronyx later uses the Time Gate to bring his companions from the past into the present, to help in their fight against Jie Revorse. Once Jie is defeated, they are sent back through the Time Gate to their time.Dr. Robert Leingod would later conduct research on the Time Gate 300 years later. While there, they found out it was actually a conduit to the Fourth-Dimensional Space, created by Fourth-Dimensional Beings, and that the time travel is actually a counter-measure to ensure that no one uses it to get into Fourth-Dimensional Space.
Later, the Time Gate spoke to the research team, and told them the chilling news: mankind had started using Symbology too much, and thus posed a threat to the Creator. As such, judgment would eventually come and all of mankind would be eradicated. The research team returned to Moonbase devastated.
Later, the children of the research team went to the Time Gate. Sophia Esteed, using her power of Connection, was able to use the Time Gate for its real purpose, and opened a gate to Fourth-Dimensional Space.
A relic that can be used to travel through time, said to be located on the planet Styx. The Time Gate has an artificial intelligence inside that acts as a sort of judge. Only those approved by the judge may use the portal to travel through time. The current science of the Pangalactic Federation cannot tell us who created this device, when it was created, or what its purpose might be. The science that allows the relic to enable time travel, and the method used to resolve time paradoxes are also completely unknown at this time.