Best UnderPromotion Endgame Compilation

here's another that should meet your criteria:

I love that one! So simple and yet so necessary to make a rook. May add it to the OP.

Here's another one I think you might like:

I know it wasn't necessary to take it all the way to mate, but I did.

Here's another nice one that absolutely needs an under-promotion to win:

@drdos7: Good underpromotions even without Loyd's underpromotion dual which is brilliant for other reasons! I've seen one study with at least 5 rook promotions so 4 is not the max but the consistency of concept in a relatively lean position is most appealing!

@drdos7: Is this 5 rook promotions? Is there a cook/dual? Notice I pushed some units around. Btw, not sure b3 is the best starting square for the black rook. May depend on soundness and content lines.

I'll have to take a look at it when I get home from work.

Btw, Here is an even more dramatic simplification. Much harder to test and also one with a choice of starting positions for both rooks - if sound. This is probably where the composer started as the pawn on a2 was clearly added later as a cookstopper. If this one works it is likely due to a more effective fortress shielding the king than in the original. There is yet another area for investigation which is the place of white king. Haven't looked at that at all!

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This is a very simple one, but I have a challenge for you guys. One thing that has been nagging me about this puzzle is that I haven't been able to find a way to put the 2nd black knight into this position so that black has every single piece, and the puzzle still works. If any of you can find a way to add a black knight here and rearrange the pieces but keep the concept the same, where the knight checkmate with the queen on a1, I will give you 100 trophies, not joking. This problem would be perfect of there was a way to add the 2nd black knight in there!

Here is another under-promotion study:

This is what also nagged the original composer (Otto Blathy) and is the reason that white starts the solution with 1. Kf2xNe1. Just another mishap of life! Note that the knight is not the only unit to disappear during the solution; some pawns have to go as well. And a rook in the original position.

P

So is it impossible to get another knight in there?

Here is what I have on this one:

I suppose many have tried to get it there and failed or it would have replaced the original in the popularity polls. But actually Blathy did realize his goal of beating the complete black army with minimal force plus a slow excelsior plus an underpromotion. You only chose to skip the first move!

Because the 1st move is obvious, he has to capture, any other move loses. I wonder if it's theoretically impossible to have both knights in a queen oscillation knight underpromotion timing problem like this. Possibly because the extra knight would end up permanently guarding the mating square.

Here you are, now I expect my 100 trophies :

1st move can't be a trivial capture, the original puzzle had Kxe1, which I omitted. Also, your knight ruins the purpose of the problem because the pawn has to choose whether to move 1 square or 2 squares to time the Nxb3 when the queen is on a1, yours leaves no choice.

I knew all of that stuff, I was just being silly.

I came really close but failed. The problem is b2 has to be a pawn so the bishop can't go to a1 once the queen moves. A knight on a3 instead of a bishop wouldn't work because a pawn would have to be on c4 to block it, which would defend b3. A knight on c2 instead of a rook would be checking the king. A knight on a5 would need alot more pawns than possible to keep it blocked in, and the same pawns defending b3 problem would arise. It might be fully impossible.