In one sense, Rxd4+ is easy to spot: given that you have told us there is a tactic available, no other move makes sense. However, full marks should only be awarded if you can *prove* Rxd4+ is good, and this is much harder!

This move seems to be where Black's defence falters. Maybe 22...Kc6 was called for, with the idea 23.Qxg6ch Kc7 or even ...Qd6. After the King move, White's next is out of the question. Having said that, the knight on d4 is very powerful, and only a demolition charge will clear the obstacle on the d-file - the only one available to White's rooks.

Very hard, but I'd play 23.Rxd4+ with the idea of winning a pawn. 23...cxd4 24.Qxd4+ Kc6 25.Qd5+ Kc7 26.Qxa5+ etc.

White has now a winning game, despite the material deficit: rook for three pawns.

Has to be 24. c5+, opening lines for the rook and bishop at once.

I would play 24.Qxd4+ with the idea of confining the monarch to less squares. This appear to lead to a quicker mate for white.

!! Superb move. It would not have been so very easy to look past the 'obvious' Qxd4ch - good enough for little more than equality.

I was wrong for a change. But, why is it better? I ask because I would feel confident, as nothing else would come into consideration for me besides 24...Kxc5.

The point is that after 24... Kxc5, 25. Rc1+ adds the rook to the attack, and checkmate should follow in short order.

25. a4, whence 26. Bb5+ would force Kxc5, and then 27. Rc1+ should lead to mate.

Yes I considered that, but after Bc8 black is preparing to return the exchange - with advantage to black!

Bc4, maybe, but I reckon I'd have chosen the Q move myself, as clearly winning.

I'd play 26.Qb6+, in hopes that black would blunder with 26...Kd7?? to allow a skewer that would win the Q with 27.Bb5 On the other hand, that would be too easy.

Though 26.Qb6ch also looks to be winning, this check is way stronger, keeping the Q in the centre, and offering the BK fewer options.

This would be my second guess.

I would play 27.Qxd4 to win back a pawn.

I would not have guessed this move, even though, I looked at it. But, I had Ghost Vision as I was worried about the Q harrassed. This would be true if white were to play 27.Qb6, instead. Even if not, I would have thought that this brings the Q out of play, but that's not true.

29...d3 was still possible, here, not that it would have saved Black after 30.Qc4ch.

My thinking would be 30.Ba6+ which appears to mate in 2 because if black plays 30...Kc7, then 31.Rc1+ appears to be mate. What I forgot is that black has better options.

That would've been my second guess.

I'd play 31.Rc1+ where mate appears to be soon.