The witness is one of my favorite games of the last decade. I wonder what it would be like in 2D.
The main mechnism, much like in the witness will be drawing lines and connecting points. However, because this whole thing is 2D, we can't have panels like the witness does. Instead the puzzles are embedded into the world.
This means the lines you draw have to interact with the world. There'll be various kinds, some that function as walls, as platforms, as ladders, or even some that interact in more complex ways (conducting electricity? elemental?).
The lines will be "pulled from" terminals, and the color of the terminal will determine what kind of line it is. For each terminal, there's a corresponding receiving terminal. Connecting the two terminals unlocks things in the world and also makes the line between them permanent.
Lines are constrained by sigils embedded in the environment. These sigils are fixed (having them be movable would be pretty complicated) but they can interact with the environment somehow.
The puzzles in the witness don't do anything other than be puzzles and it's pretty key to the witness. Having them interact with the environment in the homage makes it a very different game.
They could interact with the world in a purely visual way, non gameplay.