Meisterwerke

W is missing a R, Q, and the KB. The QR was obviously captured on b1, since the WN on a1 was there before bxa3, and prior to bxa3, there was no way for the WQR to get out. Thus, the WKB was captured on g6 and the WQ on f6. B is missing a P and a R. The BR was clearly captured on b3, since there was no way for W's a-pawn to get to the b-file, and it could not have promoted prior to axb3.

The BN on h8 was there prior to hxg6 (for similar reasons to the WN on a1). Thus, the WR on h7 and the BR on h6 got there via h5 and h6, not via h8. This means that the WN on h5 got there after the two rooks were on h6 and h7. In order for the WR to get to h7, two things must have happened first: 1) the WP on f4 must have been there in order for the WKR to get out, and 2) the WP on g3 must have been there in order for the WKB to get out to be captured on g6, freeing h7. Thus, before the WN got to h5, there were pawns on f4 and g3. So the WN must have gotten to h5 via f6.

Now, when the WN moved to f6, B's c, d, e, and f-pawns were all on the 7th rank (the e-pawn was there because the WN is on f6; the d-pawn was there because if it had already moved, the BKB could never have gotten to b8). Both B bishops were on their home squares. So when the WN moved to f6, the BK must have moved out of check (or not have been on e8). The only place for it to go is to d8. This means that the BQ was not on d8, but it could not have moved from d8, so it was captured there.

Thus, the original BQ was captured on d8, then the B a-pawn promoted on b1, capturing the WQR in the process. The original BQ never moved, the actual BQ is a promotee, its first move was Qb1-a2 (since both a1 and c1 were occupied).

Solution by Roger Lipsett