Aloy explores the ancient ruins beneath the Citadel and unravels the unbelievable truth of Project: Zero Dawn
Aloy has just destroyed the Focus Network of the Eclipse and must now travel to Sunfall. Sunfall is located in the area above the Eclipse base. Follow your quest marker and don't forget to override the Tallneck in the desert on your way there.
Upon arriving at Sunfall, head for the Citadel Courtyard. Watch the cut-scene and a woman will introduce herself to you as an ally. If you go to her this will start the Traitor’s Bounty side quest where you must save Uthid. Should you choose to ignore this side quest, continue on to the Grand Balcony and look to the left. You should find a path.
Climb down the path and follow it onwards. Once you reach the bottom, Sylens will ask you for your full commitment and that you must have completed all other errands before you continue. Enter the area to progress and initiate a cut-scene.
Once you get into the Facility, explore around for any information about Project: Zero Dawn. Enter the viewing room and watch the hologram video. The first one will be of General Herres discussing about the situation of Earth. There are also several data points that you can scan for more background story and information that you may piece together.
You will also encounter some of the Shadow Carja. Take them out to continue on with your quest.
After killing the Shadow Carja, keep exploring the facility and you will encounter Dr. Sobeck's hologram video. She will discuss about Project: Zero Dawn and the introduction of GAIA.
After the cut-scene you'll have to head on out to the Processing Room and then head onward to the Central Projects Room.
On your way there you'll encounter more Eclipse troops, take them out but you'll also have to restore power to the locked door.
Look for the geo-therm reboot systems. One of the geo-therm reboots systems is missing a piece. Search for its piece in one of the rooms in the level just above the geo-therm reboot room. Once you have it, put it in the slot and scan the FARO CODEX machines for the correct codes and then head on back to the now unlocked door.
After killing the Eclipse, you should be in the clear. Search for Sobeck's Office and examine the console. A cut-scene will initiate and the quest will be completed.
