I know, I couldn't believe nobody had done The Witness before either. But here we are. The Witness is a 3D, first-person puzzle game in which you, presumably someone trapped in an ironic punishment after making an ill-advised deal with the devil, explore an island made of puzzles. And solve those puzzles.
The island itself is very beautiful, and made of a few roughly defined areas - biomes, almost. A foresty bit, a ruined village, a desert, a sort-of swamp, a beach, and so on. Each area has a new set of puzzles, which are simple at first, to teach you their fundamental rules, but grow more and more complicated.
They mostly involve drawing lines on a little puzzle pad, sometimes in response to stimuli in the world. I was very bad at some of them. There's one group, for example, where you have to trace the line up or down depending on the pitch of a corresponding string of notes. It was here I learned that I apparently have a tin ear. There's another kind that's sort of like a manual Tetris, and I had no idea what the rules where even as I was randomly drawing shapes and succeeding.
Whether my inability to understand the rules is a failure of the game, or a failure of my own grey matter is, I will admit, entirely up for debate. I believe there is a sort of second, secret layer to the game where once you solve all the puzzles, the island itself becomes one huge giant puzzle, but I have never got that far.
The Witness is by Jonathan Blow, who did Braid, and so if you Google "indie games" it is usually one of the suggested titles that appears. The algorithm thinks it is an example of an ur indie game. Which is interesting in and of itself, and probably means The Witness is worth playing. But honestly, defo avoid it if you hate puzzles because that's literally all it is. It's also cheap in the Steam Sale right now.