How to Unlock All Challenge Modes (Photos) in The Killing Antidote

1/4 A2 Control Room

To access the Central Control Area, examine the photograph pinned on the noticeboard. You can find this bulletin board in the initial room of the game, the same space where you activate the wall switch to open the set of double doors.

2/4 B1 Water Distribution Chamber

On top of the middle water tank, there’s a toy airplane. Interacting with it grants you access to the Abandoned Hangar.

3/4 A3 Surveillance Office

On the outside of the locked office door, you’ll notice a heart painted in blood. The access code to this room is 1314. Inside, there’s another bulletin board with a photograph that, when inspected, unlocks the Despairing Mourners.

4/4 E0 Air Vent Passageways

After evading the Devourer, you’ll find yourself in a wide tunnel featuring a large fan. Once you open the door in this section, you’ll encounter a short staircase. The Pumkin Baby statue is located here, and examining it will unlock the Spook Castle.