All Codes in The Killing Antidote

1. A2 Storage Room. You can only open one door, behind it there are about 5 enemies waiting for you. After destroying them all, examine the walls on the right to find the code 5678.
2. A2 Shotgun Room. Don't rush. Look through the window with a net, behind which you can see a shotgun. Press T to change the angle and shoot the button by the door. Take the shotgun with ammo!
3. A2 Operations Room. You will find yourself in a warehouse. Destroy all enemies, climb onto the open container using the nearest crate and look through the glass into the equipment room. The code on it is #520.
4. A2 Data Room/A1 Captain's Room. You will get to the captain's room. Kill the enemy, take the revolver, examine the computer and on the second tab, reset the password to 0000. Also open the locker in the captain's room by entering the code 6090 (written on the wall at the entrance).
5. A3 Heart Room. At the end of the corridor there will be a code door. The code is indicated in the audio recording from the fourth floor. To save your time, enter 1314.
6. A3 Office with a butterfly poster. Killing it will create a shortcut to the elevator on the third floor. The computer has the code 1180, which opens a nearby locker with a pulse grenade.
   
7. A3 Planning Department. Through the warehouse and the double door, go up the stairs to the third floor. Open the door with the blue keycard. Enter the planning department on the left, crouch and defuse the two mines. Examine the computer. There is a locker. The code is 0210 (on the back of one of the photos hanging on the board).
8. A3 Duty Room. In the office opposite there is an outfit, a computer and an exquisite statuette. In the room next to it there is a door with a code panel. Enter 3964 (on the poster nearby) to get to the save room.
9. A4 SMG Room. Return to the third floor behind the blue door and look for a landing at the end of the corridor. Go upstairs, kill a couple of enemies. In the closed room on the right there is a submachine gun, but the password is unknown yet. It is hidden in a poster with gifts. Enter 3758 to open the room and take the submachine gun.
10. E2 Loading Area Office (Stealth Section). Keep in mind that the mercenaries will run to you several more times. In the far room there is a code door. The code is 9842 (indicated on the posters in the area).
11. B2 Body Bag Room. Clear the floor. There is a hole in the floor on the left, and it leads to the beginning, so go forward. In one of the rooms there is a code door. The password is 2940. It is shown on the right if you open the door.
12. A4 Storage Room. Almost all will be strengthened with red crystals. In the far room, open the locker by entering the code 9885. You will find an orange keycard.
13. A4 Office/A4 Elevator Control Room. As soon as the corpse is on the button, you can climb the boxes to the opened door. In the room behind the door, there is a combination lock on the cabinet. Enter 6083. The code is formed from the numbers outside, on the landing, if you stand so that only four numbers are visible. Inside is a hard drive. Enter the back office, examine the lockers to find the code 3974. Enter and take the Z emblem.