APOLLO was the AI responsible for providing the knowledge of the ancient world to humans after the terraforming process.
APOLLO was a part of Project Zero Dawn, and was a subordinate function to GAIA, like HADES. APOLLO was a crucial part of the terraforming process. It was meant to teach the history of Earth and humanity's past achievements to the future humans. This was to help them continue being an advanced society, and maybe not make the same mistakes.
Shortly after GAIA Prime was finished, the team received a hologram from Ted Faro. Faro had purged the APOLLO subordinate function out of fear that it would cause the new humans to get the same "disease", causing them to recreate the Faro Swarm and repeat humanity's other mistakes. Shortly after, he vented the room, killing all nine Alphas of Project Zero Dawn. Because APOLLO was purged of most of its knowledge, the later humans such as Aloy didn't know of the past achievements, and this caused them to live in primitive tribes. Because of its short life, not much is known about APOLLO or its personality.
- APOLLO was named after the eponymous Greek and Roman deity, their patron god of knowledge as well as music, art, poetry, oracles, archery, plague, medicine, the sun, and light.
- There is a distinctive possibility that APOLLO can be recovered, or that it wasn't actually purged at all. For example, Aloy purged HADES, but never destroyed it as she thought.