Elysium was a hermetically sealed habitat created for the scientists and workers of Project Zero Dawn and their immediate families (or two persons of their choosing) to live their remaining natural lives protected from the Faro Plague. After Zero Day, the day on which life outside of such environments was finally eradicated, for all intents and purposes ending life on Earth, they would live in this habitat, the last living organisms on the planet, until they died naturally, marking the de facto end of life on Earth.
Elysium was not designed to repopulate the planet, due to limited supplies. An Elysium habitat could only sustain a starting base of 2000 individuals for up to 100 years. Should the population grow, the inhabitants would be dead within 30 years. To prevent this, all inhabitants were required to be sterilized. This existence was very unappealing to some of the Zero Dawn members, who instead chose medical euthanasia.
The Alphas of Project Zero Dawn never made it to Elysium with their families, as GAIA was incomplete at the time of evacuation to Elysium. The Alphas remained in GAIA Prime for the rest of their lives to finish perfecting GAIA's subordinate functions.
- Elysium is based on the afterlife in Greek mythology, which was reserved for mortals chosen by the gods, the righteous, and the heroic. They would remain there after death to live a blessed and happy life and indulge in whatever employment they had enjoyed in life.