The Keys to the Kingdom

The Keys to the Kingdom is main story quest in Prey (2017).

Overview
I left myself instructions to destroy Talos I if the Typhon broke out. The process requires two arming keys, mine and my brother’s. I managed to secure a fabrication plan for mine, and Alex is waiting for me in the Arboretum to give me his.

Objectives

 * Fabricate your Arming Key
 * Get Alex’s Arming Key (Arboretum)
 * Go hear Alex out in his office
 * Alex is in hiding until Dahl and his tech officer are disabled
 * Alex is ready to meet in the Arboretum
 * Protect Alex from Dahl

Walkthrough
This mission is added automatically to your journal when, during Restore From Backup main mission, you get Morgan's Arming Key fabrication plan. You get it after using the computer in the Command Center in the Deep Storage. You can craft Morgan's Arming Key by using one of the fabricators, one of them is in the Command Center. Find the key from the list of the items that you can craft and use materials to get this item. You only need 1 unit of mineral materials.

Warning - If you missed your chance to use the fabricator in the Deep Storage's Command Center you can still complete this objective later without any problems. You can complete it by using any of the fabricators on the station.

Get Alex’s Arming Key
This quest is continuously updated as you make progress in other missions from the main story. First, you must reach the Cargo Bay - you go there during This Side Up main mission. Also, you must unlock the door to Cargo Bay B which is done during Shipping and Receiving main mission. When you clear the Cargo Bay B from Typhons you can go through it. A rather linear path takes you to the passage to a new location - Life Support.

When you enter the Life Support you automatically receive a new main mission called Reboot that gets a priority over other missions. Reset the reactor to complete this quest. The result of this action is that you remove the station's blockade issued by Alex.

Escape the Reactor
Once you've completed the Reboot mission, a conversation with Alex Yu will initiate and the man will propose a meeting in his office. However, your objective now is to escape the reactor room. It won't be an easy task, as the lower part of the northern stairway was destroyed and you won't be able to use it again. What's more, monsters have appeared in the area, with two Technopaths among them. It's advised to attack those creatures one by one by using, among other things, the Recycler Charge and the Q-Beam. Additionally, if you've unlocked the storage earlier you can find 4 turrets there. You can set them up and use against the enemies, but keep in mind that if you're using typhon Neuromods you can also be attacked by them.

You can go up (or to be more specific to level -3) in two ways. The first method requires you to go to the north-western corner of the reactor room where you can repair a fuse box, fixing the nearby grav shaft.

The second method requires a lot of climbing. In this case you must start by reaching metal balconies located directly above the reactor. You can then select one of the footbridges leading to the western balconies. Once there, start jumping to platforms located above to reach fans and other larger objects. Watch out for Mimics, avoid contact with the fire (you can clog the gas pipes with the GLOO Cannon) and constantly use the Artax Propulsion System to reach more distant ledges. You should soon reach the upper part of the northern stairway. This one wasn't destroyed and you can use it to reach level -3.

Reaching Alex Yu's Office
Continue your journey towards the exit of the power plant (you can complete Assist Mikhaila Ilyushin side mission along the way). Once back in the large room on level -2, you will be informed about the high concentration of gas and the risk of an explosion. This means that you must stop using any firearms, as well as attacks that might produce sparks. This problem can be tackled in several ways. You can kill the enemies you encounter by using different tools (like, for instance, the combination of GLOO Cannon and a melee weapon), avoid any contact with them, or lower the concentration of the gas. If you've chosen the last option, you need to explore the area in search of control panels. You can use your Repair skill on it - fixing all three of those control panels will eliminate the threat.

Regardless of your approach, head back to level -1 and go through the passageway leading to Life Support. Once there, go through the passage to Talos I Lobby located right next to the Security Station on level 1. Afterwards, enter the main elevator and disarm the active Recycler Charge. Now head to Arboretum.

Once in Arboretum you will receive a new message from Alex Yu containing a code to the grav shaft leading to his office. Use the code to complete your task and reach the destination. Once in the office, a new main mission - Before I Give You the Key - will start and it will be your next task.

Fending off the Operators Attack
You will gain access to the next part of the described mission once you've completed Before I Give You the Key mission - after scanning the Coral located outside the station and trying to send the scan. The final part of the mission will fail. What's more, military operators sent by Dahl (starting from this moment you will encounter more of them throughout the whole station) will appear in Alex Yu's office in Arboretum. You can either engage them in combat or get away from the office as quickly as possible. If you decide for the former approach, remember to use both EMP Charge and Disruptor Stun Gun to stun the enemies and allow you to easily attack them.

Alex will contact you regardless of your choice, informing you that he won't leave his hideout until you've taken care of Dahl's tech officer. Taking care of the tech officer is a part of Repo Man, an assignment that begins after an unsuccessful attempt to send the acquired coral data (after Before I Give You the Key) You'll need to travel to Shuttle Bay to find and take care of Kaspar, Dahl's tech officer.

Taking Care of Dahl
Taking care of Dahl himself (interestingly enough, this step is not mandatory) is a subject of a few optional tasks which are described in Dahl section of our guide.

Here is a short recap of the whole situation. Sometime after the visit to his shuttle (the initial objective of Repo Man), you'll be contacted by the admiral himself, who will threaten to murder the remaining station inhabitants kept in the cargo bay by depriving them of oxygen supply. Morgan can save the day by taking on Dahl's Ultimatum. The quest sees you travel to Oxygen Flow Control Room on level 2 of Life Support in order to take care of the admiral.

Once you've reached Dahl's dwelling, you can proceed in two ways. Morgan can simply kill the target (watch out for military operators and Dahl himself, as he is armed) or use the Disruptor Stun Gun to incapacitate the opponent, provided you've received a mission to dispose of Dahl from Dr. Igwe (Incapacitate Dahl). This will allow Dr. Igwe to perform a surgery that will revert Dahl back to his original state, introducing you to a new ally for the final phase of the game. More details on the second approach can be found in Side Missions -> Dahl.

Meeting Alex Yu
Unlocking this part of the final mission requires you to dispose of Dahl's tech officer (an adjoining story quest - Repo Man). If you've managed to eliminate the target, Alex will invite you to his office in Arboretum.

Note - Before you decide to meet with Alex, make sure that you've completed all of the side mission thus far. After advancing to the finale, all of the unfinished side missions will be cancelled (apart from Who is December? and Incapacitate Dahl).

Meeting Alex can go one of two ways. If you've took care of the Dahl's threat by completing Dahl's Ultimatum, Arboretum will be free of any extra defensive measures. Do not enter the office itself, but simply access the hidden control panel found on one of its outer walls. Using the panel will unlock access to Alex's panic room and initiate a conversation with your target.

Note - You may also search the panic room itself - the room contains a TranScribe device that is one of the prerequisities of Dear Future Self.

If you hadn't took the time to find Dahl or ignored Dahl's Ultimatum completely, Arboretum will be scoured by additional military operators, including Dahl himself who will attempt to access Alex's panic room. As can easily be imagined, your job is to deal with the admiral, either through killing him, or by using incapcacitating means, and taking care of the operators nearby.

Alternatively, you can hide and wait for the time limit to pass. Dahl will manage to get the access to the bunker and will shoot Alex after a short conversation. The event is still counted as a successful completion of the objective, as you can search Alex's body for plot items needed to unlock the final stages of the game.

During the meeting with Alex (provided he hasn't been killed by Dahl) you can behave in two different ways. The first approach is to listen to the whole conversation and collect Prototype Nullwave Transmitter plan from him. Soon an Apex typhon will appear and Alex will lose consciousness. Once zero gravity comes about to Arboretum, you can ignore the unconscious Alex or approach him and search the body for a TranScribe and Alex's Arming Key.

The second approach requires you to kill Alex. This can be done either during his speech or after he loses consciousness. In this situation you will also receive the Prototype Nullwave Transmitter plan, TranScribe device and Alex's Arming Key. Additionally, once you kill Alex, you will receive Push the Fat Guy trophy / achievement.

Regardless of your approach, you will unlock two new main missions associated with different endings of the game:
 * A Mind Without Limits main mission is about constructing the Nullwave Transmitter device and using it to destroy all Typhons.
 * Perdition main mission is about using both arming keys (that of the main character and the one you've just collected) to initiate the station auto-destruction sequence.

Trivia
The name of this quest could be a reference to a fantasy-adventure book series written by Garth Nix, where a boy must collect seven keys to conquer a world named 'House', which has a vertical layout similar to Talos I.