Survive Sevastopol with Prima’s Alien: Isolation Walkthrough.
Your first objective of the mission will be to Find a Way to the Lower Floor. Step off the transit and head inside Apollo Transit Security. Loot the room and do some light reading on the Sevastolink terminal, then exit and go left, passing under the Towerlink Transit System sign and heading through the Reception door. Head up the short set of stairs in front of you and choose to Place Weapons on the conveyor belt. If the option isn't there, approach the door and then set the weapons down. Either way, when you're properly unarmed the door will unlock and allow you through.
The next door is locked as well, and when you approach it your objective will update to Check the Apollo Sales Tour Schematics. Turn around and choose the option to Use on the uncovered table in the room, allowing Amanda to check the schematics.
After a short conversation with Ricardo, your objective will update to Power Down the Conduit. Take a closer look at the schematics you were just studying to see the number 4930 circled on top. Approach the nearby door and enter 4930 to open it.
Move forward and save your game, then head to the right and down the hall labeled Right Hemisphere Overview. Pass through two doors and make a left turn when you can't go any further forward. Follow the corridor in the only direction you can go until you reach a room with an audio log sitting on top of the middle console. Play the audio log, then look to your right and choose the option to Use Security Access Tuner.
The previous action will update your objective to Shut Off the Turbine Ventilation. Backtrack the way you came, passing by the save game mechanism and following the corridor labeled Left Hemisphere Overview. Keep moving along until you go through the Core Observation door, approaching the right console and choosing the option to Use Security Access Tuner.
Time for an updated objective, and this one wants you to Access Conduit Through the Turbine Shaft. You're once again going to backtrack the way you came, but prior to entering the Left Hemisphere Overview corridor with the save game mechanism, enter the now open turbine shaft and choose to Climb the ladder.
Your objective will update to Access Apollo, and to do this, you'll need to follow the ventilation shaft until you drop into a room. There are three exits, but the one you're looking for is called Right Hemisphere Servers. Go through that door and into the one on your right, then pick up the Gas Mask from the desk.
It's been about a minute, so your due for an objective update, and this time you must Find Apollo's Human Consultation Control Room. Exit this room through the door to the right of the Sevastolink terminal, passing into the Right Hemisphere Server room (unlabeled) and moving around it in a counterclockwise fashion. When you find the Monitoring Control Room door, go through it to reach a corridor, then follow it to the end and go through the Human Consultation Control door at the end.
Once inside the Human Consultation Control room, move to the opposite end and choose the option to Use Security Access Tuner, then turn around and save your game. Your objective will now require you to Search the Left Server Bank Console, and will update again a few seconds later with Search the Right Server Bank Console.
We chose to exit out the Right Hemisphere Servers door and backtrack down the corridor as it curved to the right, taking the only door at the end and on the left. This is the room with the Right Hemisphere Servers, and the console you're looking for is in the far left corner of the room from where you just entered. Approach it and choose the option to Use, updating your objective to Use Access Tuner on Dome Terminal to Gain Access.
While you're still looking at the console that you just interacted with, turn to your right and move to the corner of the room, jumping inside a ventilation shaft and following it through. When you emerge, search the center console for the option to Use Security Access Tuner, which you'll soon find to be impossible.
Your objective will update to Find a Way to Reduce Apollo's Security Capabilities. To complete this, locate one of the two ventilation shafts along the edge of the room and choose the option to Use Button on the right side. Climb into the vent, then look for a console that's hanging from the ceiling. Check both sides of the console and select the option to Use when it pops up. If you don't see the option, try the same thing on the other vent, then return to the circular room and try the option to Use Security Access Tuner again.
Completing the mini-game will provide you with a new objective, and this time you must Consult with Apollo. It's simple enough. Just wait for the big dome thing to go crazy, then let Amanda and Apollo have their chat. When it's all over, the latest and greatest objective will be to Investigate Central Reactor.
Consider saving your game after disengaging from Apollo, then get to work on another objective, which is to Exit Apollo Beneath Core. Turn around from where you saved your game and Climb down the ladder, then Climb down one more to find yourself in a room with a Sevastolink terminal. View it if you want, but when you're ready, step on the platform and choose the option to go To Engineering. This will give you a final sendoff objective which asks you to Get to Reactor Core.
Continue to Alien: Isolation - Mission 14: The Descent.