The Witness is a first person puzzle game about solving puzzles on boards where you mostly draw a line from one point to another, following rules divided in themes - by physical location, mostly - that the game never explicitly tells you. You have to figure out from very simple puzzles what the logic behind it is and from that solve harder puzzles until you complete everything in an area and move on to the next mechanic. I had an interesting time with that game, it's not perfect and I'm unsure about the whole first person movement aspect of it, but it's a good puzzle experience that I would entirely recommend.
After a short intro, you emerge into an island divided in many sections. There is a desert ruin, a castle, forests, a swamp, greenhouses, and plenty of other areas where you go and solve puzzles. Walking around is a pain. You move so slowly and the fast travel - boats that navigate around the island - isn't nearly fast enough. You then arrive in front of puzzle panels and need to solve them in order to trigger the opening of a door or the activation of a mechanism. My favorite kind are the ones where a series of about ten puzzles are lined up in a row and you can just solve them one after another, being able to quickly see the others if you start doubting your logic. The ones I disliked the most were ones where you have to take screenshots or draw things on paper in order to figure them out, because the information isn't easily available.
At the beginning of the game, you'll encounter simple enigmas; This grid has white and black dots, draw a line from the beginning to the end where all white and black dots are separated. It's simple enough and you understand the mechanics quickly. Then you get to weirder stuff and you need to align the puzzle panel with trees or rocks in the water, or you have to move around to get the sun to reflect just right on the whole scene, it's a bit rough, the 'logic' of the puzzle is quite simple - i.e. you have to align the panel with rocks to see where lines go - but then you fumble around trying to figure which perfect angle is required and that can get frustrating and unfun. Some puzzles de-activate the puzzles before them if you fail so you can't bruteforce them, also an unelegant solution.
While many puzzles are just there to unlock the next puzzle, some will have impact in the physical world. Solving a puzzle in a certain way might move a platform left or right, raise or lower specific sections of a maze, etc. Some puzzles go the other way around and involve your movement in the physical world in how you solve them, the paths you walk, the sound the ground makes when you traverse mazes, I didn't enjoy those very much either. Playing with no sound made it quite difficult or - again - having to draw maps of what I should do wasn't very interesting. And sometimes the logic can be a bit unclear - do I need to separate all of these pieces or do I just need to make them fit in the line? These usually aren't too bad, because you can try them again easily, since they're static line puzzles.
The goal of the game as I could figure it out was to shoot lasers at a mountain to unlock something. I found only one story bit as I was playing - an audio log reading a very length passage from a book or a speech by some famous person - and my eyes just glazed over as I tried for a small number of seconds to figure out what this had to do with anything in the game. I feel that The Witness is hurt by its format. Granted, the physical movement around give it a Myst-like quality and some of these puzzles are pretty clever, but I also would have enjoyed a game that presented me a list of 600 puzzles that I had to solve one after another on static screens. Add a few sliders to change the position of the light where required, make all movement-based interactions purely occur by clicking around a puzzle panel, and I would've been happy.
But no, The Witness is a bit more than just puzzle, it's a lot of busywork as well, that's why I don't feel that it's a 5/5 game. The puzzles are clever, what it does with its fantasticly rendered 3d world is pretty interesting, but these things don't combine in any way that I really enjoyed. After having shot five or six lasers at that mountain I stopped while trying to solve the Desert Ruin puzzles, I couldn't figure out how to get the light to reflect at some of them, oh well!