The Apocalypse (世界崩壊 Sekai Hōkai?) also referred to as the Day of Lavos (ラヴォスの日 Ravosu no Hi?) occurs in year of 1999 AD at 1:24 when Lavos is set to destroy the world in Chrono Trigger. Three individuals from other time periods arrive to defeat Lavos, preventing the Apocalypse from occurring.
As Lavos erupts from underground and sprays explosive spines into the atmosphere, which fall on the entirety of the planet's crust and wipe out almost all of life and human civilization. while The planet becomes practically uninhabitable, and humans must rely on what little food they can find to survive, while they use Enertrons to rejuvenate themselves. Even the landmasses seem to have changed shape.
Many of the robots that "survive" the Apocalypse come under the control of Mother Brain and begin to take over the world.
Three-time travelers appear to stop Lavos from destroying the world. They defeat Lavos's outer shell and then move into its innards to defeat "Inner" Lavos and then the Lavos Core. Thus, the Apocalypse is prevented.
1999 A.D. has a futuristic metropolis appearance. It is similar to Present other than the fact that the cities are in domes, and ruins cover the landmasses.
1999 AD is the only major time period that is not directly available to explore. If the party travels to this time, it is forced to engage Lavos in battle. The party can access Lavos a bucket with a time gate in the End of Time that acts similarly to a regular Time Gate, or the teleporter to the right at the Millennial Fair (from the new game+ only), or use the Epoch, or by defeating Queen Zeal at the end of the Black Omen. If accessed by using the Epoch after it has been outfitted with wings, the vehicle crashes into Lavos, entirely avoiding the battle with its shell, but this removes the save point and Time Gate inside Lavos.
Relevance to Chrono Cross
Upon reaching access to the Dead Sea, Serge and the party discovers a dimensional distortion consisting of various destroyed futuristic cities surrounding a large tower made of fused buildings, all laying within a sea frozen in time.
It is later revealed that the area is made from the alternate future where Lavos was not stopped from destroying the world and succeeded in causing the Apocalypse.
A unique game over sequence is shown if Lavos defeats the party. The sequence shows Lavos destroying the world, and the perspective then shifts to a lab in which three people, a director, a supervisor and an operator, are witnessing the coming apocalypse. Locations all over the world are indicated with red dots and labels, showing that they have been destroyed. The lab itself begins to crumble; the director commands the other two to leave immediately and stays, being crushed under the building.
The sequence then shows the planet in its entirety (as seen from space). It goes gray and a message appears, accompanied by Lavos' shriek: "But... the future refused to change." In the DS version, it says "In the end, the future refused to change."