I'll be honest, I didn't like The Witness as much as I wanted to. It's a stunning game and wonderfully atmospheric, but the puzzles get really dense, and I just don't have the patience (or, I suppose, the brain) to get my head around the later-game stuff. Taking a break just made it worse: When I came back a few weeks later I'd completely forgotten most of what I'd learned, and so had to replay much of the early game to get re-acquainted with it. By the time I hit the tough stuff again, I was done with it—again—and accepted that whatever mysteries it holds will be hidden from my eyes forever.
That's not to suggest that it, or any game, has to be finished to be enjoyed—just an FYI that The Witness is super-tough. It's not really an issue at this non-existent price, though. You could fire it up, toodle around, and enjoy the scenery for an hour, and still count it as a win.
The Witness is free for the taking until April 18. After that, the critically-acclaimed 2014 action-RPG Transistor will take its place.