Shortest-proof-game challenge

53

Got bored this evening...

The positions are getting interesting. I hadn't guessed it could be done quickly with nearly all the white units on Black's side of the board. But it's not hard to understand after seeing it done. The promoted knights don't have as far to travel.

My first try looked more like tygxc's position.

I think 49 moves is the shortest for this challenge, which can be done with the square d5.

Since daStrwbrry's game was so much shorter than my first try, I looked for a related problem I might do better with. It may be a litle silly as a chess problem, but it's a challenge and someone might want to try it. It has an easy part and a harder part.

What is the greatest number of unmoved white units that can remain on the board in a legal position with White to move in which any of 15 white units can move to the same square? What is the quickest way such a position can be reached?

My first try this time gave me a 52-move game with four unmoved white units.

@6836

Yes, 4 units and 52 moves. E.g.

Non-unique proof game in 15.0.

How much can you shorten my first try of 27.5 moves for this position?

@6840

Shorter:

Another way to make it legal

That's a trickier way. I'm sure someone can shorten this.

@6843

Shorter:

1 move shorter without bQd3. Is it possible to shorten more?

@6845

I think it is shortest. I have been looking at ways to capture Ra8 at its initial square and thus saving the move 10...Rb8, but I could not find a way.

I can shorten your proof game by 1 half-move:

Very nice!

I tried both the Bg4 and Rd7 strategies but never thought of combining them; BxNf6 was a pain to deal with.

@6847