The Witness is a game with no tutorials, no overt explanations. It is a puzzle game, but it makes no deliberate effort to explain how its puzzles work. It teaches only through experience and observation.
This is clear from the outset of the game, in which the player finds him- or herself looking down a tunnel at a door from a first person perspective. The game doesn’t explain that WASD is used to move, nor anything about who you are or where you are. You just need to play around with the keyboard and approach the door.