Last move must have been pawn from d2-d4 check. which is possible.
Black must have captured atleast one piece to get the c2-pawn to where it is. White is missing 1 bishop.
Black must have captured atleast 2 pieces to be able to promote a pawn to one of his two bishos. White is missing 2 knights.
white have manouvered his bishop out via b2 AFTER the pawn captured a piece on c2, because b3 had to have been played after bxc2 (only way pawn is there, since it could not have come from the d-file since that requires too many captures (b-c-d-c) this is possible. the bishops must have danced around a little before g3 was played, the rook have stood it's ground.
The rest of the pieces seems to be on quite logical squares which should be possible to manouver.
I'd say the position is legal.
An original retro problem #25
Must be said though that I have never tried myself on such puzzles before, so I might be way off on this one.
I don't know about d2-d4, but -1.d2xRc3 seems to work fine (other white captures cxBd3 and hxPg, black promotes on a1 or c1.)
What's interesting about this position is not just finding the correct solution, but understanding why other tries don't work.
White's last move could have possibly been:
1) d2-d4+
2) e3xd4+
3) d2xc3+
4) fxg6+ en passant
Now, Remellion already gave the correct answer. However, why would other tries fail?
I know en passant fails (-1. fxg6e.p.+ g7-g5 and now both Black's dark bishops are promoted, but there's only one missing pawn), but I'm still working on the other three.
Thank you, chaotic. I have added a note to self regarding the en passant. Basically, the position is improved with a pawn on e6 instead of e7. The latter invalidates en passant too obviously, while the former is slightly more interesting and in line with the problem's theme.
what black piece or pawn did white capture on c3 to be able to have a pawn on c3 for cxd4+? White doesn't have enough pieces so that black could've landed a pawn on c3, and the light square bishop was never on c3. I don't think white has enough pieces so that the a3 rook could've been a promoted pawn either?
@shoopi: I think you should leave the pawn on e7. Were it on e6, there wouldn't be a problem with -1. hxg6ep g7 -2. dxRc3 etc.
I also see the problem with d2-d4+ and exd4+ also - somewhat related, but different at the same time. Looks sound.
@MrUlekeiv: The last move was not cxd4+ - it was dxc3+. The piece just captured can be identified. If you were asking about exd4+ instead - it becomes necessary to consider where the black bishop promoted, how/when the bottom right got into position, and which black pieces were captured where.
No tricks this time, just straight up retroing!
Do note, however, this one is quite basic
Is this legal?