Shortest-proof-game challenge

@6337

Shorter

The count of posted attempts is up to seven. I'd say it qualifies as a good challenge.

Maybe I should come up with more positions like this.

This is a first try at a proof game, and it could be a lot shorter.

@6344

Are the coordinates right: h8 bottom left and a1 top right?
If yes, then the last move must have been g7-g8=B# or f7xg8=B#.
If no, then the last move must have been e5xf6 e.p. #.

yes but cxb5#

@6352

Is the diagram upside down or not?
Is the white king at b1 or at g8?

The white king is at b1, according to the coordinates shown in the diagram. You said the last move must have been a promotion on g8. EvinSung tried to tell you, using the fewest possible number of words, that you overlooked the possibility of the white bishop being original and the last move being cxb5#.

I wonder who will be first to find a 25-move or shorter proof game for this fairly simple position.

@6354

So the position is:

Yes. EvinSung is constrained by a tight quota on words posted per day and thus is forced to make very short posts, which are sometimes cryptic.

A start:

18.5 moves