...a thematic element similar to the mate in 8 in the "Petrov" thread.

Good. Very good.

I fell for the trap with Ba1. Fail, I then remembered who set it so looked for 'tricks'
en passant, can somebody castle, what was Black last move etc...nothing.
Went back to original idea.

Spoiler
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@greenpawn34

Close!

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Ahh...

I was too quick in running the pawn for a stalemate and wondering why there
was tiny flaw 1.Ba7 or 1.b8=R can be played in my first line.

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@greenpawn34

Solved.

I thought this looked like a problem that chess engines would have a problem with so I gave it a try.

Fritz saw +30 to white and seemed happy, but after 10 seconds suddenly saw the mate. 10 seconds for a chess engine is an eternity for a mate in 4.

So I gave Stockfish a go. It saw mate in 16 instantly and then seemed to stop. At the 10 second mark it spammed the screen with messages too fast to follow and then displayed mate in 4. I think it was astonished!

Tried Komodo and it took over a minute to find the mate.
And I'm running Fat Fritz (which is supposedly an alpha-zero clone) and it still hasn't found the mate after 10 minutes.

So, well done! You've confused some chess engines, at least for a brief while.

@wyndavies said
I thought this looked like a problem that chess engines would have a problem with so I gave it a try.

Fritz saw +30 to white and seemed happy, but after 10 seconds suddenly saw the mate. 10 seconds for a chess engine is an eternity for a mate in 4.

So I gave Stockfish a go. It saw mate in 16 instantly and then seemed to stop. At the 10 second mark it spammed the scree ...[text shortened]... after 10 minutes.

So, well done! You've confused some chess engines, at least for a brief while.