Two Devil Knights Deliver Checkmate

This game started as a Réti before transposing into familiar Semi-Slav territory. I won't spend much time on the opening because the really interesting part begins when White's position really got off the rails.
The first warning sign came with 17.Nxd4, after which Black began harassing the queen and putting pressure on the c3-knight. White could still have stabilized the position, but 18.Nde2?! was far too passive and left some serious weaknesses behind.
Even then, White wasn't lost. In fact, after Black's 18...Ne4?!, there was one remarkable way out.
But White missed it.
And after 19.a3??, the position collapsed almost instantly.
What followed was that Black’s pieces began invading White’s position and, rather than retreating when attacked, simply stayed there.
At some point, queen was attacked by two pieces at once. White still can't take it.
Eventually Black offers the queen one final time, and this time White is forced to accept.
That's when the Devil Knights finish the job.

When Every Piece Is Hanging, But Nothing Can Be Taken

The Devil Knights

Just have a look at the final position.
There is just something almost intuitively wrong about those two knights on h2 and h3.
It is generally considered common chess knowledge that the knights on the edge of the board are often misplaced, and that the knights belong near the centre. A knight on the rim is dim. But in this game, Black has managed to put both knights on the h-file, standing directly next to each other, and they completely suffocate White's king.
The knight on h2 gives the check and controls f1; the knight on h3 controls f2; the bishop on b7, activated by the crucial 24...d4!, cuts off g2; and the rook on e8 takes care of the e-file.
Almost every Black piece contributes something to the final mating construction. Even the rook on c8, the one piece not directly involved in the mate, had already done its job earlier by making White's queen miserable on the c-file.
What makes the finish even better is the sequence that led up to it.
After 22...Nf6!, White attacks the knight on h3, but can't take it.
After 23...Ng4!, Black leaves the queen on e3 hanging, but White can't take it.
After 24.Rd3, the queen is attacked by two different pieces, and Black responds with 24...d4!, once again refusing to move it. Neither capture works because of ...Nxh2#.
And finally, after spending several moves leaving pieces en prise with complete impunity, Black plays 25...Qg1+!! and deliberately hangs the most valuable piece of all.
This time White has to take it.
26.Nxg1 Nxh2#

Final Thoughts

It's remarkable how quickly this game went from a fairly normal position to just an absolute slaughter.
White's 18.Nde2?! was already asking for trouble, although Black didn't punish it in the most accurate way. After 18...Ne4?!, White still had the remarkable defensive resource 19.Qxe4!, giving up the queen to alleviate the pressure.
It was really 19.a3?? that crossed the point of no return. After 19...Nxf2!, White's position disintegrated within only a handful of moves.
But the reason I wanted to share this game isn't simply that White lost quickly.
It's the strange logic of the final attack.
Black keeps placing pieces where White can apparently capture them. Yet every time White reaches for one, there is a tactical reason why it is untouchable. Eventually even the queen joins the collection of hanging pieces, except this time White is forced to take it.
And waiting behind it are two knights sitting on the worst possible part of the board.
h3 and h2.
Two Devil Knights, and checkmate.