A pair of interesting puzzles

Hello!

I'll present you two puzzles you can try. These both are invented by me, I think the other one is already solved, but of course I would love to see someone doing it better, here is the rules of this puzzle:

1. construct a position, which is a checkmate with the most possible amount of pieces contributing to the checkmate. Conditions:
- the position can be as fantastical as you like, no limit of amount of pieces, but it must include the king that is checkmated.
- it must not contain any pieces that are not contributing the checkmate. In other words the position is only legit if you take any piece out, it's not a checkmate anymore.

My record is 11 pieces, including the checkmated king. I'll reveal this at some point unless someone happens to arrive with a same kind of solution.

My other puzzle is much more devious:

Basically you must arrange all the pieces of both sides (8 pawns, 2 knights, 2 bishops [dark and light squared], 2 rooks, queen and king) in a manner that no piece threatens any opponent piece.
Further conditions, which must be met:
- The position must be legal so no double pawns. No pawn can be behind an opponent pawn. Bishop can't be placed in an impossible square, for example: white bishop at h1 and white pawn at g2. En passant doesn't apply.
- All possible moves (no matter who has the turn) must result any piece being under threat (this means the moved piece threatens opponent piece[s] and/or is being under attack itself or allow another ally piece to threaten opponent piece). In other words: The position is not legit if any piece can move into a square which doesn't result any piece being put under attack.
- No piece (even if it's supported by another ally piece) can be placed next to enemy king and it couldn't legally capture the piece.
- Both sides must have a mate in one, but only one move can do it. In other words: the position is not legit if multiple moves can deliver mate in one.

Example:
http://www.chessgames.com/perl/fen?fen=rb1rnNbB/q1p1pp2/2Pp4/3P1Bp1/1p2P1Np/pP3P1P/P2kn1PR/RQ5K

I personally appreciate positions which are asymmetrical, not many pieces are immobilized (in other words: pieces have as much freedom of movement as possible) and the checkmates are not obvious at first glance (in best cases it could take some time to even find the right move). In this way, the positions can be truly pieces of art!

Another position where the white mate is not obvious at all, although both armies are rather cramped so it's not that beautiful: http://www.chessgames.com/perl/fen?fen=qnb5/rrppp3/p4p2/PpPP1Ppn/1P2B2p/B2NP2P/6PR/bk2NQRK

I must clarify: en passant doesn't apply in the position itself, but of course if a pawn moves two squares from 2nd rank it can be captured with en passant if such is possible.

Here's another one, made by someone else (I really like this one :))

http://www.chessgames.com/perl/fen?fen=Q7/3npnbb/N2pkprr/1p5q/pP1PKP1p/P1pNP1pP/2P3P1/2B2BRR

These are really clever, thanks for posting them. I haven't worked out one of my own yet, I'm a little too busy at the moment, but it's an interesting challenge.

Easy lichess.org/editor/Q2Q2Q1%2F1QNQNQ2%2F1NQQQN2%2FQQQkQQQQ%2F1NQQQN2%2F1QNQNQ2%2FQ2Q2Q1%2F3Q2KQ%20w%20-

shadowx, that's not a correct solution. Read the conditions again.

"- it must not contain any pieces that are not contributing the checkmate. In other words the position is only legit if you take any piece out, it's not a checkmate anymore."

In your position you can take plenty of pieces out and it'll still be a checkmate.

A king when not in the corner has 8 flight squares. The maximum number of pieces that can attack these squares are 8 (using only pawns). There will be one additional pawn which will deliver the checkmate. A total of 8 + 1 + 1(king) = 10 pieces. With this idea, you can come up with checkmates like these.

http://en.lichess.org/editor/8/8/2ppp3/2pkp3/2Ppp3/1P6/8/8%20b%20KQkq

http://en.lichess.org/editor/8/8/8/1PPk1P2/1PP2P2/1PP2P2/8/8%20b%20KQkq

It seems like a checkmate containing 11 or more pieces is impossible as it'd require a piece which controls a fraction of a flight square on average. What do you think?

That's very good Ashura! However, 11 pieces is indeed possible, it's a bit tricky though, I'll reveal it soon unless it's been discovered here first.

I admit that your second solution is very close to what I've constructed.