What is the maximum number of moves in a position of Crazyhouse?

We know that the maximum number of moves for a given colour in a legal position of standard chess (or at least record so far) is 218.

What is the record we can come up with for Crazyhouse?

Note that moves can be:

1. moves in standard chess
2. piece drops of a piece onto any empty square, or a pawn onto any empty square except on the 1st or 8th rank

A reasonable starting idea might be to have an empty board with just the two kings and White having all other pieces in its inventory. Then (let's say the kings are on e2 and d7) you have 8x2 king moves, plus piece drop of bishop, knight, rook, queen on any of 62 squares (62x4 moves), plus piece drop of a pawn on any of 44 squares for a total of 8x2 + 62x4 + 44 = 308 possible moves.

Note that, due to the stacking nature of pieces and pawns, we cannot count them individually. We may only count with what is on top of the stack.

446 moves

Disclaimer: this answer is based on the premise that we account for white moves only, and it treats having a full set of enemy pieces as having 5 options to place something.

``````[FEN "K1QQQQ1Q/Q7/Q7/6Q1/1Q6/7Q/Q6B/1QQQQQnk w - - 0 1"]
``````

White has promoted to a queen a maximum of 15 times, with a complete set (Q, R, B, N, p) still at their crazy disposal. The last move was Ng1. White now has

• 2 king moves
• 28 vertical queen moves from eighth rank
• 3 lateral queen moves on eighth rank
• 31 diagonal queen moves from eight rank
• 14 moves for the queen on a7
• 15 moves for the queen on a6
• 21 moves for the queen on g5
• 20 moves for the queen on b4
• 16 moves for the queen on h3
• 16 moves for the queen on a2
• 7 bishop moves from h2
• 26 vertical queen moves from first rank
• 2 lateral queen move on first rank
• 28 diagonal queen moves from first rank
• 217 placements (41 à 5 + 3 à 4).

or a total of 446 moves.

• Move Qa8 to a7 to increase number of moves. Jun 1 at 7:29
• Knew it! Well spotted, in fact same is true for Qh8-h7. I'll add this once I excluded further increasing of the like. Thanks Zizy Jun 1 at 11:40
• Also ditch rook while you are at it, vertical and horizontal rooks reach 1 extra square and the king is no longer in check (the last move would be Qxsomething). I guess you can improve further by moving Qg8 to g5 but I haven't counted moves in that case. Jun 1 at 11:56
• Yes, g2 unoccupied is on my radar. Qg5 makes me doubt I'm even close to max Jun 1 at 13:36
• Your improvement of your answer is better than mine :) But if you moved the b8 queen to b4, I think you squeeze a few more moves from it.
– D M
Jun 2 at 21:45

I began the auction with a bid of 350 moves. Optimization are abound to be found.

``````[FEN "NQQQQQQB/Q6Q/Q6K/Q6R/Q6R/Q6R/Q5RB/nQQQQQBk w - - 0 1"]
``````

Here is the receipt:

• Qa2-a6: 11*6
• Na8: 2
• Qb8-f8: 11*5
• Qg8: 10
• Bh8: 7
• Qh7: 11
• Kh6: 3
• Rh5-h3: 6*3
• Bh2: 5
• Rg2: 10
• Bg1: 5
• Qf1: 10
• Qe1-c1: 11*3
• Qb1: 10
• & 3 different pieces, pawn, knight, and bishop, in White's inventory*35 drop squares.

If I count correctly, this improvement on Peter's answer is is 432 moves. Basically, I tried to get a queen on every rank, file, and diagonal - although the long diagonal with the kings is empty, which may be a way to improve it.

``````[fen "KQQQ2QQ/Q7/7Q/7Q/Q7/Q6Q/Q6b/1Q2QQnk w - - 0 1"]
``````
• Here is are some improvements: +wRa7, +wRg2, and swap for wBh2 (Black still has a legal last move with bNg1). They all add more moves then they take way, while leaving pieces of their type still in the inventory. Jun 2 at 10:53
• Problem here: What was blacks last move? Jun 2 at 13:45
• @PeterFischer How is there a problem? White's and Black's last moves is rather simple: QxNf1+ Ng1. There's more then enough pieces to go around for a capturing last move. Jun 2 at 18:59
• As usual, why do I see ghosts? Also, Qxh3-Bh2. Thx for pointing this out (and sending me right back to square one) ;) - anyway, a nice concept here, was completely beyond me, hats off @D M. Jun 2 at 19:08
• I counted wrong...
– D M
Jun 2 at 20:44