Throughout the game there are multiple pink cubes, these cubes go along a set path when observed by the player. Fifteen pink cubes have been discovered so far. These fifteen do not appear to be linked to one another as they can be done in any order except for one of them which has to be obtained the very first time you enter the puzzle's room. These cubes do not appear to have any effect on any other area. Of the 15, only 13 are obtainable through regular gameplay, one of the 2 "non-regular gameplay" pinks is in a noclip area, where you need to be able to walk through walls, and the other "non-regular gameplay" pink requires a clipping glitch.
There's No Way In[]
The path to the cube is blocked off after Leap Of Faith, Logic 101 or A Jump Too Far has been solved. These puzzles trigger a transformation of the There's No Way In room and it becomes impossible to access the pink cube secret room. It must be accessed at the very beginning of the game.
At one end of There's No Way In in its initial version, there is a set of green-colored stairs with a yellow and black border. Walking down these stairs and then back up them will bring you to a room with two pyramids, one cyan and one magenta.
The pink cube is behind the cyan pyramid. Looking at the cyan pyramid triggers the pink cube and it will be audibly moving toward The Character. The pink cube will will reveal itself and will follow a path down the cyan pyramid, audibly under the floor, up the magenta pyramid, and audibly down the other side. The character must be looking at where the pink cube is audibly for the cube to complete the journey.
Three Paths In Sight[]
The first pink cube can be found in the gallery located at Three Paths In Sight, its path borders the room starting at the left and going around clockwise till it, on the right, disappears.
The second pink cube is bugged and is normally unobtainable. There is, however, a clipping glitch that can be used to obtain it. This pink cube can be found by walking to the very back of the gallery and towards the open window into Finding The Seams. You can clip to the cube by covering the opening with cubes, apart from a man-sized hole to the side. Then enter using the hole you created; you should notice that the cubes you placed earlier are missing. Exit back into the gallery but using the side without the hole you created. The teleport will not activate and you will find a pink cube path almost identical to the normal Three Paths In Sight but inside a glitched gallery which is not meant to be seen.
Alternatively, while in the room leading to Finding The Seams, you can run through the right wall with no-clip and find the cube.
Window Of Opportunity[]
One can be found at the Window Of Opportunity. Transport to blue then walk around the transporter window so the red can be seen but don't trigger the transporter, now the other side is green. Transport to green and repeat the walk around, now the green side is pink. The pink cube follows the path in the shape of the number two.
Down The Rabbit Hole[]
The pink cube is Down The Rabbit Hole at the bottom. Chained jumps is the only way to reach the bottom since there is a Disintegrator Field in the shaft. Timing jumps precisely when The Character hits the Jump-pad pushes the jump-pad down. The initial fall to the jump-pad gives momentum to quickly traverse down.
Cry Me A River[]
The pink cube is inside the fake wall which also has a fake ceiling, use cubes to pillar upward and at the top is the pink cube.
Managing Resources[]
The pink cube is behind the door to the left. Use cubes to either build a staircase or pillar upward to get up the fake stairs where the pink cube is.
A Wall Without Stairs[]
After getting up the wall, crossing the appearing platform, and getting to the bottom of the Jump-pad, there is a wall at the back of the jump-pad shaft that is made of green cubes. The pink cube is behind the wall.
Link In A Chain Reaction[]
Between the window to the Yellow Gun platform and the sign there is a fake wall on the right where the pink cube is.
Four Different Exits[]
The pink cube is in the room just above above the ground-level entrance. Use the Yellow Gun to move the yellow cube close and use the cube for a lift.
Taking Baby Steps[]
A stairway materializes as you walk forward. Jump to fall through and walk forward through the wall to find the pink cube.
The Butterfly Effect[]
Underneath the Jump-pad used to get to The Butterfly Effect is a fake floor leading to the pink cube.
Déjà Vu[]
Stand on the pink ring, while looking at it, use blocks to pillar upward to the pink cube.
Impossible Paths[]
The pink cube is unobtainable without Noclip. It is located underneath the black circle on the ground between "WTF?" and "HMM..."
The Chase[]
Enter the chase. When you see The Black Ghost float upwards, turn back and down the green staircase. There is now a door there. Behind it is the pink cube.