dzechiel: White to move (25?). Material even. "Medium."
Sorry to get a late start, but my family took me into Los Angeles last night to see a play, and we didn't get home until very late.
Looking at today's position, it seems obvious that white needs to open the g-file in order to get the attack up to speed. The first thought is 25 Nh6+ as this is very forcing, however after 25...gxh6 26 gxh6+ Bg6 it appears that white has now self blocked the h-file and the attack will run out of steam.
So, it seems that the right way to sac the knight is
Now black has five legal replies (some better than others):
Let's deal with them. The worst of the bunch is
25...Kh8 26 Qxh7+ Qxh7 27 Rxh7#
Only somewhat better is
25...Qxf6 26 gxf6
and black is down a queen with a lousy position. Then there's
25...Rxf6 26 gxf6
and black is down an exchange and still has a lousy position.
OK, this is a much better try. It looks like the black king will make a run for it, how can white take advantage?
White gets in a little zwischenzug before moving the knight to h7. Black can move the king or take with the h-pawn, but g5 is now available for the white rook. Let's try
26...hxg6 27 Nh7
On the black rook.
27...Rh8 28 Rg5
and black will go down a queen for a rook. OK, lastly there's the move that makes it all interesting
25...gxf6 26 gxf6+
Once again black has several legal moves:
26...Qg6 or 26...Bg6 allow 27 Qxh7#
26...Kf7 27 Rg7#
26...Qg5 or 26...Qg4 allow the rook capture with check. Ugh.
26...Kh8 27 Qh6
This was the hard move to find IMHO. The threat is 28 Qg7#. The only good way to stop this is
27...Rf7 28 Rg7
Now the threat is 29 Qxh7+ Qxh7 20 Rxh7#. I think at this point that black has to give up the queen with
28...Qxh3 29 Qxh3 Rxg7 30 hxg7+ Kxg7 31 Qxe6
on the bishop and the d-pawn. I think the advanced black pawns will fall like ripe apples and white will win in the endgame.
At any rate, it's well beyond time to check.