• Start a new game.
  
• Interact with the note on the wall with LMB (left mouse button).

• Leave the house.
  
• Go right, then right at the first intersection, then left at the second intersection.

• Go around the altar and pick up the key next to the skull.

• Return to the road but take the opposite path this time. You'll be attacked by a skull and teleported to a dungeon.
  
• Follow the linear path until finding a girl on the way.

• Approach her to unlock:

Game will automatically close at this point. Launch it again and click on 'Play' to continue from the Dungeon.

• Once at the dungeon again, turn around and head to the intersection.
  
• Pick up the flashlight from the ground and take the left fork.
  
• You'll reach a dead end:

• Turn off the flashlight with E and continue forward.
  
• Once you reach the ritual, turn around and try to leave. You're now trapped.
  
• Go back to the ritual and approach the girl to trigger the ending sequence.