Here is the solution. The explanation follows.
Here is another, where Cryptic Clue n°1 is understood as
Queen-side (pun with matri-cide) castling by Black.
There is plenty of freedom in this puzzle, as shown by these two examples.
After move 14, the situation is (up to White's moves and possibly captured Black pieces)
and in this position,
g4 comes with check. There can't be any discoveries, so the White King is either in h3 or f3
PROOF THAT h3 IS IMPOSSIBLE
16. ... g3 follows, so the pawn wasn't captured, so the King moved, and it didn't move to g3 or g4. But a few moves later, we have 19. ... Nd7+ meaning that the King is then either in f6, e5 or c5. If the King is in h3 when g4+ is played, then moving to the second row makes it too far for him to reach f6, e5 or c5 in time (all Black moves would need to be King moves and the only target square would be e5, and this is impossible due to 18. ... Qf4+). Therefore g4+ is followed by Kh4, meaning that a white piece protects the King from check by the Queen. But then there is no way 17. ... Qh4+ can happen: the whole diagonal would need to be free for the Queen to move, so move 17 by White would need to remove the King from h4 and free the Queen's diagonal.
The Bishop in e4 was captured some time earlier (as well as the Black e pawn to allow the Bishop there in the first place).
WHERE IS THE WHITE KING AFTER MOVE 19.
It can only be in f6, e5 or c5. But c5 is impossible due to the sequence of checks by the Queen. f6 is possible only if there is a white piece at f5 AND the Knight at g8 was captured. It is not really in White's interest to spend time capturing Black pieces, given that Black is to deliver checkmate at the end. So e5 seems more likely. Note that e5 implies that the Queen gets captured at move 19, which is not in our interest either but coincides with Cryptic Clue n°1.
WHAT THE FINAL POSITION TELLS US
We know that Nf3 is mate, which means that the White e and g pawn, as well as the Ng1 are gone. So is the white Queen, consequently. One of the pawns can conveniently serve the purpose of capturing f3 and the Bishop e4. The Queen, on the other hand, can serve the purpose of letting the Black rooks free, so that they can help checkmating in the end (otherwise Black is poor in material).
White captures the B Queen at move 19, but also there are exactly 19 moves where White offers their Queen to be captured.
The King's closest friends are the Queen and Light square Bishop, both of which are in a position to capture Black's mating material (the Rook at a6) but don't interfere.