Forbidden Legacy is a Side Quest in Horizon Forbidden West issued by Alva in The Base. You can access it before starting The Wings of the Ten. As part of our Horizon Forbidden West guide, we're going to explain everything you need to know about Forbidden Legacy.

Forbidden Legacy: Overview

Horizon Forbidden West PS5 PS4 Side Quest Forbidden Legacy 1
You can start Forbidden Legacy by speaking with Alva at The Base, or talking to her in Legacy's Landfall if you're past the credits.
Type Description Recommended Level
Side Quest Alva believes data in San Francisco may help the Quen fix a defunct flood control system back home. She is determined to find it — no matter what obstacles stand in her way. 30
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Forbidden Legacy: Walkthrough

Speak to Alva in Legacy's Landfall and agree to follow her to some nearby ruins in search of some data she needs. When you arrive, a Slitherfang will appear and you'll have to defeat it. Once dealt with, you can begin to explore the area.

Using Aloy's Focus, you should find a vent on the right-hand side. Open it and go inside, then through to the other side. In here, you need to climb to the upper level, where you'll find a console. Activate it and watch the cutscene. After that, you'll need to follow Alva to a skyscraper in the distance. Keep following her until you reach a point you can use your Pullcaster on to get into the building. Climb up the inside, using the Focus pulse to locate handholds.

You'll come to a beam — use the Pullcaster to bring it down. Cross to the other side and shoot the lock on the ladder to lower it. Climb it to find a pair of Glinthawks — kill them or sneak past them. Continue ascending the tower until you reach a beam that leads toward some rubble. Use the Pullcaster to remove the rubble, then jump across to the gap.

In the next room, you can find Datapoints 'Useless' and 'Passcode Reminder Reset'. Using the information from these, approach the locked door and input the code 102023. Go through the unlocked door and scan another Datapoint, 'AGI Log: 10/1/47'. After this plays, go through the door on the left. Pull down the wall, head out, and continue climbing round the outside of the building.

Once you have done plenty of climbing and Pullcasting, you'll reach a patch of Firegleam. Ignite it, and then climb up the elevator shaft. You'll find another code-locked door in a room with some artifacts. Scan each of these, then approach the door and enter the code 402625. Head through the door and activate the console. After the cutscene, the quest is done.

Objective Log

  • Go to Legacy's Landfall
  • Call Alva at the Campfire
  • Follow Alva to the Research Facility
  • Kill the Slitherfang
  • Search the Ruins for the Data
  • Follow Alva to the Atbay Headquarters
  • Find an Entrance to the Atbay Headquarters
  • Jump to the Tower
  • Search the Headquarters for the Data on Leviathan
  • Unlock the Door
  • Search the Headquarters for the Data on Leviathan
  • Ignite the Firegleam
  • Climb up to the Ancestor's Office
  • Unlock the Door
  • Search the Office for the Data on Leviathan

Door Code Numbers: What Are They In Forbidden Legacy?

There are 2 door codes you will need for this Side Quest. The first door code you need is 102023. The second door code is 402625. You need to enter both of these in order to complete Forbidden Legacy.

Forbidden Legacy: Audio Datapoints Obtained

  • AGI Log: 7/13/47
  • AGI Log: 10/1/47

Forbidden Legacy: Hologram Datapoints Obtained

  • Leviathan

Forbidden Legacy: Text Datapoints Obtained

  • Useless
  • Passcode Reminder Reset

Forbidden Legacy: Rewards

  • 9,750 XP
  • 3 Skill Points

Forbidden Legacy: Notes

  • Completing Forbidden Legacy will unlock the Recovered Alva's Data Trophy.
  • After completing Forbidden Legacy, return to Legacy's Landfall some time later. Eventually, Alva will be stood near the Campfire. Talk to her and she will give you the Outfit Utaru Protector.

Did you follow this walkthrough for Forbidden Legacy? Tell us in the comments below, and be sure to read our Horizon Forbidden West guide for lots more help and information, including All Quests.