Carlsen–Karjakin World Championship
This time around there was an unusual amount of match strategy involved. In fact, what's interesting is that they always played the Spanish or the Italian, but in the one game where Karjakin wanted to (had to) win, he played the Najdorf.Peter Svidler mentioned a very interesting suggestion that the players should play the tie-breaks before the match, which should produce more interesting games (in particular, it should avoid game-12-style games). But in any case, I think determining the structure of the championship match is a rather neat test-case of mechanism design.