I'm interested in extremely difficult retros.....

Can somebody (SwissGambit? 😉) post some examples of difficult retros? but NOT PGs, please - I have enough of those.😀

Thank you🙂

Hmm, I typed "difficult retro" on google. This was the first result:
I don't know how to set "illegal" positions in fen, so I will just write the pieces squares.

Pieces: Kc8, Kd6, Qc6, Rd8, Rf6, Ba8, Ne8, a7, b7

Colour the pieces. What was the last move?

I'm afraid it's too easy for you though, so I will look a bit further 😉

Originally posted by heinzkat
[fen]B1KRN3/PP6/2QK1R2/8/8/8/8/8[/fen]

Actually, this retro is not difficult at all...🙁

Ever tried your hand at SwissGambit's Illegal Cluster problem(s)?

how about this (unless you know it already, it will probably keep you busy for a while 😉):



white to move and draw.

Hint: 50-move rule

Originally posted by crazyblue
how about this (unless you know it already, it will probably keep you busy for a while 😉):

[fen]nB3RbN/1kppppq1/1p4p1/1P3p2/Bp3P1n/4PrbP/2PP1rP1/R3K3 w - - 0 1[/fen]

white to move and draw.

But in that one the idea is clear immediately (that white castles and thus proves that 50 moves were made without capture/pawn move).

Originally posted by David113
Can somebody (SwissGambit? 😉) post some examples of difficult retros? but NOT PGs, please - I have enough of those.😀

Thank you🙂

Release the position

That means, I suppose, pick as few as possible pieces off the board in order to make it legal?

edit: Googled it, I suppose you need to fix the diagram (2 Black Kings)

Originally posted by heinzkat
That means, I suppose, pick as few as possible pieces off the board in order to make it legal?

edit: Googled it, I suppose you need to fix the diagram (2 Black Kings)

How did you find it given that the diagram was wrong?

"Release the position"

In essence, this stipulation asks you to find how a given (usually quite tangled) position can be reached legally. So that it really asks for a proof game but without insisting on giving all painful details of a proof game. You "only" have to find the tricky maneuver that is required to lock everything the way it appears in the diagram.

Originally posted by SwissGambit
How did you find it given that the diagram was wrong?

I guess he googled "release the position", not the diagram, and found that in a "release the position" problem the position must be leagl so the 2 kings are a mistake.🙂

Originally posted by David113
I guess he googled "release the position", not the diagram, and found that in a "release the position" problem the position must be leagl so the 2 kings are a mistake.🙂

Yes, that is what I did, sorry for being unclear.

Originally posted by SwissGambit
[fen]Nrbb4/qprp3p/PpQK1p1P/RRpp4/Brk2P2/B1P5/1PP5/1N6 w[/fen]
Release the position

Thank you SwissGambit🙂