Two-doors puzzle

The two-doors puzzle is a recurring puzzle in The Beginner's Guide. It first appears in the game Puzzle, and is later seen in Down, Notes, Island and Tower.

It has been speculated that the three dots symbolize the puzzle (2 doors on either side with the dark space in-between).

Solution
This puzzle is very simple: all you need to do is: If the player cannot figure out the puzzle for the first time, Davey will eventually help them progress.
 * press the switch on the left side of the first door, opening it;
 * press the switch again - but moving into the dark room as the first door is closing (locking you in the second room);
 * press the switch on the other side of the first door (now closed) to open the second;
 * exit through the second door (which is now open).