Good point about 2.Bxh1# - I thought any check by Black would do to disrupt mate in 2 but overlooked the defensive move is also mate !

As for 1...Rd4, you tricked me there because what was a white pawn on g3 became a black one, otherwise 2.Rxf2# works o/k.

Back to the drawing board    

As I've said, I have to use promoted pieces to present my idea clearly.

My main idea is castling, Black checks and White mates. Let's see:

I'm waiting for the confirmation of either Adrian or BDP. I hope the key is nice and sound!

Stephen_33, Even though the g3-pawn is a White piece then 1. Rf1 Rd4 2. Rxf2+ Ke5! You missed again the defensive idea. He he.

Balachandar, we are looking for a mate in 2. Not mate in 3.

I tried using the diagram in the first post, and in that, there is no rook at f6. So, mate in 3 is the shorest mate possible. 

later, I have seen that a rook has been added at f6 in the consequent posts.

The diagram at post 22 has only one solution: 1.O-O as you said . So there's only one key. However, this puzzle has 6 duals after 1...Ra3:

2.Ba2# -- 2.Bb3# -- 2.Bc4# -- 2.Qf4# -- 2.Qexe4# -- 2.Qbxe4#

But that doesn't count here . Just saying .

Great puzzle Asorski. But the key is very obvious for composers.

OK. Sorry but that was already been corrected.  The diagram at post 22 is the final and correct position. Thanks for solving.

Good to know that this has only one solution. Well I'm happy now. I have created a very complicated position with an easy key but beautiful variations!

This will be posted as my 52nd puzzle. Thanks a lot Adriandmen for the confirmation!.

I can't help but think that the problem can be economized, and some of the duals eliminated. Here's what I've got so far.

                    White mates in 2

I think Asorski added pieces to confuse the solver. Like the mindcracker.

BigDoggProblem, My earliest version of my puzzle was very identical to you. Here is my earliest version but I rejected this because I want to open the h-file for the Rook-check  on h5. 

Adriandmen wrote: "I think Asorski added pieces to confuse the solver. Like the mindcracker."

You are correct Adriandmen. "Sometimes in a battle of problem ideas I have to give up something to get something!" In my final version (post 22), obtrusive pieces ruins the puzzle a bit but the key (1.O-O) added more weight. The  Rook on h1 withdraws from it's active post, a common theme   very common to almost all problem composers.

In my earliest version, I remove the pawn on g5 to give the Black King "some fresh air". Also the solver would think that the white Rook on h1 will stay there because of the set mate: ...Nh5 1. Rxh5#!

I believe, my final version is much harder than my earliest version.

Good to see that all came together in the end Asorski. Your puzzles are usually satisfyingly complicated - I got reasonably confused !

Just one small complaint - I tried to make sense of your corrected puzzle (see post #16) in the Analysis Board but it wouldn't allow castling because you had disabled it !  Didn't we have this problem once before ?

I do note that you corrected this in post #22 !

Thank you for a nice compliment stephen_33.

You know, I always try to make my puzzles difficult and beautiful. More often, I put more effort on the difficulty of the key move. Beautiful problems are sometimes easy to solve.

Back to puzzle 52: I did not intentionally disabled the castling option. Maybe I just did not click the "allowed castling" box. As you can see from the top, castling is the main purpose of this problem. 

BigDoggProblem,  You're right the Rook on h1 is just a bystander. Expert solver will notice immediately the Rook there doing nothing. They will easily see the castling maneuver as a key to the puzzle.

Maybe I could effectively make this (with no promoted pieces) in a mate in 3 or mate in 4.

it's mate in three moves..1. Ne6xNg7+  N x N 2. Bc4+  Qe5 3. QxQ+ mate