Phony Benoni: Judging from the number of comments this is not one of Capablanca's famous masterpieces, but there are some interesting points even in these unknown games.
Take 3...c4. We've all been taught not to play this move against a Colle or Stonewall setup. "Don't relax the tension!" and all that. But Capa does it here, and it's absolutely the right decision.
Why? Ask yourself, "What is the purpose of the Bd3 in these situation?" Partly, it's the kingside attack, but more importantly it's the support for the e3-e4 push at a point where White can profit from opening up the center.
Usually, the opportunity for ...c4 by Black comes after White has played c3, allowing the bishop to retreat to c2. From there, it still participates in kingside action and still supports e3-e4--which has been given added oomph because it's precisely what White wants to play to undermine the c4 pawn.
But in this game, White has not played c3. The bishop has to retreat passively, and White is never able to get the activating e4 push in until it's far too late.
Then there's the little tactical interlude beginning with 17...e4 18.c4. I get the impression White is just trying to mess with Capablanca's head, planning to answer 18...exf3 with 19.Qxf5. So Black just counters by protecting or moving the knight, White moves his knight, and we get on with life? Right?
Not quite! Now, Capablanca sees no advantage in releasing the tension, so he just keeps improving his position elsewhere. White goes along with the gag until 21...Qb5! smacks him upside the head.
Now the threat is 22...exf3 23.Qxf5 Qe2, threatening mate and the unprotected bishop on d2--which works because, at this moment, White doesn't have the move Rf1-f2 available. After 22.Ne1 Qe2 White is in a world of hurt; if, say, 23.Qc3 to protect the e-pawn, then 23...Bxf4 24.exf4 e3 25.Bxe3 (25.Bc1 Qf2+ 26.Kh1 Qf1#) 25...Nxe3 with threats of mate on both f1 and g2.
So White gives up the knight and mounts a desperate assault which at least allows him the moral victory of a mate threat. This goes nowhere fast, and Black soon has the chance to trade queens. Naturally, the great master of simplification and endgame play ... spurns the trade and scores with a mating attack of his own.
You don't mess around with Capa.