Like safe codes, many door keycodes are randomly generated, but several of them are static - meaning they're the same every time you play. Below, you will find a list of the static keycodes in one section, and a list of where to find the randomly generated keycodes in another.
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rnAll Door Keycodes

Once you get access to the Recycler and the Fabricator, you will be able to start building things out of the material you recycle. Eventually, you'll be able to Fabricate Neuromods - once you find the plan. 
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rnWhere To Find The Neuromod Fabrication Plan

The Huntress Boltcaster is one of the most useful weapons in Prey. It can serve as a distraction, or be used to trigger buttons or computer screens that you cannot reach. 
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rnWhere To Find The Huntress Boltcaster

The Shotgun in Prey is one of the most useful items. It's great for taking down Phantoms, which are the second-tier of alien enemies, but you'll have to get it first.
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rnWhere To Find The Shotgun

Crafting Shotgun Shells is one of the most lucrative uses of the Fabricator in Prey, so long as you have the plans.
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rnWhere To Find The Shotgun Shells Fabrication Plan

Prey's Disruptor Stun Gun is great for taking down mind-controlled humans in a non-lethal way, and you can find it pretty early on on the second-floor of the Nueromod Division simply using your GLOO Cannon as stairs.
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rnWhere To Find The Disruptor Stun Gun

Having watched a lot of Prey streams, I knew the Psychoscope was a big part of the game. That little device that lets you scan alien enemies and work toward getting unlocking their abilities should be top of your wish list when you get in the game.
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rnWhere To Find The Psychoscope

Many safe codes in Prey are randomly generated, but a select few of them are always the same. Below, you'll find the safe codes that are the same for every playthrough in one section, and where to find the randomly generated codes in another.
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rnAll Safe Codes

When you first exit Morgan's apartment into the testing labs, you'll find a room called the Simulation Debriefing. This room has a safe in it, and the code to the safe that was written on the whiteboard has been erased.
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rnSimulation Debriefing Safe Code

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You may have already figured this bit out: Prey has hidden fire alarm safes. Not every fire alarm is just a normal fire alarm. Hit them three times with your wrench, and they might open up to reveal a hidden safe. 
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rnHow To Spot Hidden Fire Alarm Safes