Penguincw: What a game!
So early on, the position gets locked up. The only real pawn break was actually h5 by black, which never showed up in the game. The locked position reminds me of Kramnik vs Nakamura, 2011, where Naka won that game. Hard to believe this started as a Ruy Lopez.
Black is able to crash through on d3 using Alekhine's gun, and it gets real interesting after time controls is met.
For a while the position is at a standstill. Nakamura plays 43...Qd7, and forces Caruana to maintain the balance, and he does by shuffling his rook, ex. 44.Re1.
Note if 43.Bxc7, then 43...Qd7. If 44.Ba5, then 44...Nxb2 45.Qxb2 Bxe4 and look at the pressure on f3. 46.Rf1 Rxf3 47.Rxf3 Qd3 48.Qf2 b2, and uh-oh for white.
The key combination Nakamura missed was 46...Qxe4 47.Qxe4 Bxe4 48.Rxe4 Nxb2 and that b-pawn becomes very dangerous. Not easy to see, but if he saw it, it would've been a huge advantage for him.
I think at some point there's a 1...Qa6 combination that puts the white bishop on b8, way out of play, but I forgot where it is.