Survive Sevastopol with Prima’s Alien: Isolation Walkthrough.
When the mission begins, you'll be aboard the Nostromo and playing as Ellen Ripley. You might recognize the voice of Sigourney Weaver, the actoress who portrayed Ripley in movie the franchise, most notably Alien (1979) and Aliens (1986).
Your objective will be to Help Lambert and Parker Gather Coolant Cylinders, and you'll notice that you have your trusty Motion Tracker available to help keep on top of things.
Check for supplies in the room where you begin, then use your Motion Tracker to locate the direction of your objective and start heading that way.
Approach a closed door and use the button to open it, then move into the next room and head into the narrow corridor on your right. Follow this to a second door, using the lever to partially open it. To get through, crouch and crawl under it, then climb down the ladder
When you reach the bottom of the ladder you'll want to make your way along the corridor, continuously using your Motion Tracker to stay on course for your objective. When you reach a room on the right side with some blood and a body inside, turn into it to receive your next objective, asking you to Access Engineering Control to Reverse the Lockdown.
Exit back into the corridor and head back in the direction you came from, moving all the way to the room with the ladder. Use your Motion Tracker if you're not completely sure where to go, but when you're in the right spot, turn to the right and approach a door that requires a Keycard.
After opening the door, you'll be in what looks like a control room, and your first order of business is to interact with the keyboard on the left side of the room. This will update your objective for a third time, now requiring you to Initiate Nostromo Emergency Destruct System.
As you might expect, your objective is nowhere convenient, so to get there, turn to your left (from where you were standing and facing the keyboard), moving into a nearby room and then climbing into the vent. Use your Flamethrower to light the way, and when you exit, make sure to use your Motion Tracker to see if the Alien is anywhere nearby.
From your location just outside the vent, you’ll want to move into the corridor and turn to the right, then turn to the left when you can't go any further. Follow this path as it curves to the left, taking the first door that you come to on the right side. Pass through this room and use the lever on the giant door on the opposite side.
This ruckus will attract the Alien, but there is plenty of cover for Ellen to hide behind throughout the room. Evade the beast for a few moments until it gives up and goes away, then sneak through the door you opened and into the next room. Should the Xenomorph still be in the area, use the cabinet just to the right of the door to hide and wait it out. Don't forget that you can lean back and hold your breath if the creature gets too close.
When you're ready to move on, head into the corridor on the right side of the room and follow it until you reach a vent that's also on the right. Jump into the vent, then follow it in the direction of your objective which should be displayed on your Motion Tracker. This will cause you to exit into another corridor, and you'll want to go through the door to your left.
The easiest way to keep on track from here is to tell you to use your Motion Tracker. There are a lot of doors and corridors, but this device can keep you reach the target much better than a handful of instructions. It also doesn't hurt that your Motion Tracker will help you to stay away from the Alien.
When you finally reach your destination, approach it and pull both of the levers to release the self-destruct lock, then turn around and activate it using the device on the floor. This will update your objective and require you to Escape on the Narcissus.
Big surprise, your objective is on the other side of the ship. No problem, bring up your map to get a general idea, but as we mentioned earlier, rely heavily on your Motion Tracker to guide you there. The journey will be loud and you'll have poor visibility, but resist the urge to hide, choosing instead to walk with your favorite device in hand, using it to keep tabs on the Alien as you move.
After arriving at your final destination, approach your chair and take a seat. That'll trigger the mission ending cut scene. If you followed our guide and got a little lucky, the worst you had to endure was spotting the Alien for a few brief seconds.