Porter needs you to reach the Computer Core to print out The Thinker’s machine code. Unfortunately, Reed Wahl has frozen over the access chamber by throwing the Climate Control turbine into overdrive. Head to Climate Control and reset the turbine to unfreeze access to the Computer Core.
Climate Control
The direct route is locked up for now—frozen over thanks to Wahl—so you’re going to have to go a different way. Return the way you came, descend the stairs near the Gatherer’s Garden, and loop around to the right, past the ice, to find a Vacuum Bot and the Upgraded Drill impaled on a Splicer. Ride the elevator down to the maintenance area.
The fourth Vacuum Bot in Operations is directly ahead. Fend off the Fiery Brute Splicer with Anti-Personnel Rounds and Electro Bolt and claim the Incinerate! 2 Plasmid from the rear of the room. Consider swapping out Telekinesis if you have only six Plasmid Slots available (and buy another one at the next opportunity!). Pick up the Audio Diary (“Wheels Within Wheels”) near the elevator, then ride it up and use your newfound Plasmid to melt the ice.
The crystalline blocks of ice you see explode when shot, so give them a wide berth and treat them like fuel barrels—only target them if they’re truly in your way or if a Splicer is nearby! Listen to the Audio Diary (“Porter’s Legacy”) straight ahead. Duck down beneath the suspended walkway on the right and gather up the ammo and ADAM Slug in the water, then return the way you came. The Armor-Piercing Rounds will now be available at El Ammo Bandito machines.
The frozen Splicers in the next area aren’t all dead. Some are Wintry Houdini Splicers just pretending. Hit them with Incinerate! (they are immune to Winter Blast) and open fire with the Ion Laser or Anti-Personnel Rounds. Wintry Houdini Splicers are among the most common enemies from this point on, so visit a Gene Bank and outfit yourself accordingly.
Ignore the items you see through the windows on the right for now and instead continue on straight ahead, following the signs for the turbine area. Hack the vending machine on the left near the mag-lock and loop around to the balcony facing the locked door. Toss a Gravity Well over the wall to open the door and collect the ammo near the terminal.
Duck under the pipes on the right, inside the turbine area, to find the Upgraded Launcher. Continue down the stairs to the frozen turbine area and melt the piles of snow and ice scattered about to find some valuable ammo. Collect the Audio Diary (“Detonating the Tunnel”) from the terminal near the Little Sister Vent. Proceed through the door near the Health Station and eliminate any Splicers in the area.
The door on the left is locked, but you can fire a Remote Hack Dart through the gap in the jammed doors on the far side of the room. Use this to hack the door control and retrieve the Ice Storm tonic inside.
Descend the stairs toward Turbine Maintenance, following the flashing red warning signs. Continue across the catwalk to the control room and melt the ice with Incinerate! to pull the override switch and reset the climate control. Now that you reset the turbine, you can continue to The Thinker, but it’s best to spend some time exploring the rest of this area, as there’s still another Vacuum Bot to find and a Little Sister to deal with.
Operations is now crawling with Alpha Series Big Daddies, so keep your Electro Bolt (or Insect Swarm) handy and a pair of Elite Security Bots near your side at all times. Follow the exit signs south through the Climate Control area until you reach the room with the windows on the left revealing several collectibles. Ascend the stairs to the room with the large tank in the center and locate the final Vacuum Bot in the back near the corpse of a fallen employee. Descend the stairs on the left to find another Upgraded Ion Laser, an Audio Diary (“Pearl, Alone”), a Safe containing 62 Dollars, five Solid Slugs, four Rocket Spears, and the Elemental Sponge tonic. Equip the Elemental Sponge tonic immediately!
Little Sister Encounter
The Lancer will slowly make his way to the Little Sister Vent outside the turbine control area in Climate Control. Wait for the two of them to get sufficiently far enough away from the vent so that she doesn’t frighten and return to the vent as you attack the Lancer. Consider laying some Gravity Well traps before splashing the foe with Security Command. Draw him into the Gravity Well traps as your Security Bots open fire on him. Stun him with Electro Bolt if he manages to avoid the Gravity Well traps and finish him off with Heat-Seeking Rockets or Armor-Piercing Rounds.
Gather #1: Turbine Control
The first of the two Gathers is right near where you probably adopted the Little Sister. These final two Gathers are among the hardest in Rapture because you’re dealing with a large number of Wintry Houdini Splicers simultaneously. Set up several Mini-Turrets, a good number of Trap Rivets, and be sure to summon a pair of Security Bots. Consider placing Gravity Well traps near the entrances to the area, as well. Stand back in the nook behind the corpse so that you aren’t in the line of fire and fend off the Splicers that get too close while allowing your defenses to handle the rest. The Wintry Houdini Splicers can freeze your Mini-Turrets, but they’ll thaw after several seconds.
Gather #2: Climate Control
The final Gather Corpse is in the room with the large tank, where the final Vacuum Bot was located. Utilize the large oil slick to set Wintry Houdini Splicers on fire as they attack, while also making sure to cover the entrances with Trap Rivets and Trap Spears (though the latter do pose a risk to your Security Bots). Equip the Shotgun and Phosphorescent Buck and unleash Insect Swarms on the Wintry Houdini Splicers as they enter the area. Instead of staying in one place, consider sprinting laps around the room, circling the tank, so you can pick off the Splicers as they appear.
Big Sister Is Coming!
Return the Little Sister to the vent outside this room to unlock the “ADAM Addict” Achievement/Trophy and to summon the next Big Sister. Descend the stairs to the area near the Gene Bank and use Hypnotize to befriend any Splicers in the area. Summon two Security Bots, ready a Gravity Well trap, and equip your Rocket Spear Ammo or Heat-Seeking Rockets. You may even want to lay down any Mini-Turrets you have left, as you won’t need them going forward. Repair your Security Bots to keep the Big Sister distracted and continue to fire on her. Switch to Armor-Piercing Rounds if you run out of the heavy firepower. Collect the ADAM from her corpse and head to the nearest Gatherer’s Garden to collect your gift.
Follow the Exit signs back to Core Access, passing the Gatherer’s Garden in Engineering along the way. There will be a gift from Tenenbaum waiting for you if you dealt with all three Little Sisters in Operations. The gift includes the Armored Shell 2 tonic, 100 Dollars, and 120 ADAM. Splice in the Armored Shell 2 tonic along with the base version. Swap out Proud Parent and/or Master Protector, as you won’t need them anymore. Proceed through the Clean Room that was formerly frozen to access The Thinker.