The games between Vladimir Kramnik and Hikaru Nakamura and between Sergey Karjakin and Fabiano Caruana were both drawn, and while each had their moments the big game of round 2 in Zurich was between Viswanathan Anand and Levon Aronian. In their classical matchups Aronian has enjoyed a big plus score, most recently winning just eight days ago in the Grenke Chess Classic, but Anand has won the most important and the most spectacular games. (Important games: Mexico City 2007 and the Candidates' in 2014; spectacular games: Wijk aan Zee 2013 and to a lesser degree today's game.)
Today's victory was the product of some outstanding opening preparation, almost surely done in the wake of his draw with Magnus Carlsen in game 10 of last year's world championship match. Aronian does play the occasional Gruenfeld, and after this game the amount of time he takes before trying it again is likely to increase. To his credit, Aronian's first five moves or so after the surprise were very good ones; his misfortune is that he needed to find a bunch more to come through safe and sound. Inevitably he erred, and Anand was able to finish things up at the board very quickly.
That puts Anand into a tie for first with Nakamura with three points each after two rounds (they're using 2-1-0 scoring for the classical games; the subsequent rapid games will be scored in the usual way, with the overall totals tallied to determine a winner); there are three rounds to go. Tomorrow's pairings are as follows:
I've analyzed the games, but the ChessBase online viewer is down (and has been for over a day); I'll post my analysis once it's back up. (UPDATE: It's back up, and the games are here.)
Also of note: Viktor Korchnoi and Wolfgang Uhlmann played a two-game rapid match. The quality was low for the great players they once were (in Korchnoi's case, this wasn't long ago at all), but pretty high for players who will be 84 and 80, respectively, this March. Both players won with the white pieces; Uhlmann first and Korchnoi second.