Proof games

This topic is for members who like Proof game problems: in a Proof Game, the solver's task is to find a unique sequence of legal moves that will reach the diagram position on White/Black 's move number N.  Here is a famous example: 

Tibor Orban, Die Schwalbe, 1976 (Commended)

 Please note that this position is easy to reach in less than 4 moves for each side.... but there is only one way to reach it after Black's 4th move.

Click the little chessboard, follow the prompts:

dear Doggy_style,

Thanks very much for your post, but I do not see the chessboard icon on my screen. Perhaps it is because I am using safari?

Try Firefox.

Also it won't be there if your are using an iphone or tablet or anything. Needs to be an actual desktop or laptop.

Varelse1,

many thanks, that is what I am doing wrong! I will move to my laptop and have another go.

I am impatiently refreshing this topic for fun stuff. But just in case, I posted a proof game problem (not mine) two days ago.

This was so hard! It took me more than an hour...

Nicely solved, Xsi

I am using tablet that's why I am unabke to post diagrams. Thanks everyone for solving my problem

Do you have to do it in 7 moves? I got this when trying.

Err yes ?

Thats the problem you have to solve ?

You have 6 half moves of black and 7 half moves of white.

You have 6 pieces that are gone - white king pawn e2, white king knight g1, white knight bishop f1, black queen bishop c8, black queen pawn d7, black king pawn e7.

Also white has castled.

I so far have failed to manage this. I need 6 half moves to get pieces in position, 6 half moves to actually capture, and the last capture probably has to happen by some extra piece that has to move back as well.

But if it was easy then why would it be a challenge ? There must be some very nifty trick.

My best attempt so far. The queens are in the wrong position. So there is still something missing.

@DavidReti Excellent work! This took me ages, as I thought the two most likely ways to get rid of Black's e-pawn are 1.Nf3 e5 2.Nxe5, and 1.e4 e6 2.Bc4 then Bxe6. Neither works and I almost gave up, until I tried the unique path Nh3-f4xPd5 which suggests the e-pawn can be captured by the knight without moving at all.

The black king switchback is remarkable – no other piece can do the job of capturing both white pieces.

White's 8 move made this position. How did white reach this?

@Rocky64: well done! 7. 0-0 is necessary for the problem to have a single solution. The position before 7.0-0 has 2 other, much less interesting solutions:

a) 1.Nh3 d5 2.Nf4 Bg4 3.Nxd5 Bxe2 4.Nxe7 Bxf1 5.Kxf1 Kxe7 6.Ke1 Ke8

b) 1.Nh3 d5 2.Nf4 Bg4 3.Nxd5 Bxe2 4.Nxe7 Bxf1 5.Rxf1 Kxe7 6.Rh1 Ke8

The inclusion of 7.0-0 forces the K and R to stay on their original squares in the build-up play and gives a single solution, which can be confirmed with specialist software!

There is a large thread in the fun forum on shortest proof games.

@17