if we're going to plug random puzzle games on this thread, IMO the most underdiscussed puzzle game of all time is Recursed, the only game i've played which properly explores recursion as a mechanic, and (MINOR SPOILER) the only game i've played which detects when you have created logical contradictions, and for each contradiction you achieve rewards you with a secret bonus level.

If we're talking about recursion, Patrick's Parabox is another stellar pick.