Biology Sector
You can access this mission once you reach the Biology sector in the campaign during chapter 14. The door to the elevator staring this mission is on the main hallway of the building in the same room as the bench and the suit kiosk. We can ride this down an underground storage area. There is another SK1P here similar to the one we used up in space to move between the various zones except there is nowhere for us to travel to at this time. Use the bench and suit kiosk in this room if you require and then take the other lift down to the optional mission area.
Marker Containment
Exit the lift and work your way over to the unlocked door, kill the slasher that appears and continue through it. Hit the button at the end of this platform, to have it rotate around and stop in front of a door on the opposite side of the area. Enter the door the platform is now facing. As you enter, grab the audio log [Log 1/1] from the desk in front (note there is also an upgrade circuit on the floor behind this desk on new game +). Continue through the nearby unlocked door.
Use stasis to open the wire fence here. Kill the 6 twitchers that spawn at the end of the passage in front. Don’t be afraid to use the stasis canisters on the floor here to slow down their advance! Enter the door at the end of the area and follow the passage to the right.
Attempt to enter the door at the end and Carver will have a freak out. At this point, both players will have different experiences. Carver will have to defend himself against feeders whilst progressing to the end of an area that only he can see. On the other hand, the player controlling Isaac will see Carver frozen in position and will have to defend him against a number of ‘super’ slashers until he recovers. Once Carver returns to normal, the door will unlock, allowing you to progress.
Take the first right in the next area and continue through the rooms here, killing a slasher or two who try to surprise you as you go until you reach one with ice inside. As you enter this area, look to the right for an upgrade circuit [Circuit 1/4] (note there is also a Weapon Part – MKII- Rail Accelerator on the stack of crates on the left side of the main area on new game +). Continue into the room and you’ll be attacked by a group of feeders. After killing a few of these, a group of slashers will also show up. Kill them all. Continue through the unlocked door on the far side of the area.
Follow the passage here (note there is an upgrade circuit on the floor in the middle of the area on new game +) and enter the elevator at the other end.
Upon exiting the lift, turn right and take the elevator here up to the walkway above. Follow this to the end for an EarthGov Artefact [Artefact 1/1]. Return down the lift and make for the unlocked door across the way (note there is an upgrade circuit in the small sunken area opposite the lift we entered the room from on new game +). Attempt to open the door and it will malfunction.
Just like the previous malfunction, Carver will freak out again and appear to Isaac to be standing in place, not moving. Again, there is a split in gameplay here. Carver will have to fight his way through feeders again, whilst Isaac, back in the real world will have to defend Carver against a few waves of ‘super’ slashers that appear. Once Carver has returned, the door will unlock, allowing you to progress through it.
Look on the right hand wall of this room for a locker containing an upgrade circuit [Circuit 2/4]. Grab this and loot the remaining lockers in the area if you like before proceeding out the next unlocked door.
You’ll be on another of those rotating bridges. This time, you will need to flip the button twice to have the walkway face the unlocked door opposite. After pressing the button for the first time 5-6 lurkers will appear and fire at you from the walls above. Kill them all and go through the next door. Loot the lockers here and continue through the unlocked door nearby. It’s another rotating bridge! Repeat the process here and exit the door on the far side.
Go down the stairs to the left of the ladder and you’ll find a Weapon Part – Rail Accelerator [Weapon Part 1/2] near the bottom. Open the door here and kill the slashers inside. This will cause more slashers and a pair of exploders to spawn both in front and behind you. Stay vigilant and kill all the enemies before proceeding through the next doorway on the left.
Climb the stairs and head for the chest to the right. As you approach, Carver will trip out one final time. Again, this plays out for Isaac in exactly the same way as the previous two moments – carver will stand still, and you will need to defend him against an oncoming number of ‘super’ slashers. Carver on the other hand will need to work his way through feeders until he finds a red/black marker and shoot this a few times to destroy it. Once this happens, Carver will return to normal.
Go over and loot the chest for 2 upgrade circuits [Circuit 3/4 and Circuit 4/4] and a Weapon Part – Ammo Box [Weapon Part 2/2]. Climb the stairs nearby and enter the unlocked door at the top. Enter the elevator and take it back to the underground storage facility.
Use the bench and suit kiosk here if you require them and then take the other lift up to return to the Biology sector to complete the mission.
