A quick guide on how to get the Void ending and its achievement.
Void Ending Guide (Spoilers)
The Void ending can be obtained anytime in which you have access to the basement.
Find this paint-covered wall in the basement.
Click on it, and accept breaking it down.
Go inside and down the stairs to find the room from the intro.
Pick up with revolver and shoot yourself in the head.
Do this 6 times until you have used every round in the revolver.
Go down and repeat a 7th time.
You will awaken at the bottom of the well from the Affliction Tape next to the apple.
Walk around until the credits appear.