Comments/Ratings for a Single Item

P = 1, N = 3, (WA) = 3.5, B = 5, (BW) = 7.5, R = 7.5, Q = 13.5 is just a guess at middle game piece values under Alice Chess rules. Recently I thought about adding some Chu Shogi pieces to this variant. Multiplying the numbers for N, B, R by 1.08 brings us very close to the Zillions estimates that Antoine Fourrière listed in this article. Zillions values a Queen in Alice Chess as slightly lower than the total of a Bishop and a Rook (just as it does for FIDE Chess). The relatively low value of a Knight is probably because it is "Alice colorbound" (light squares on one board and dark squares on the other board).

A simple Alice Chess endgame with all chessmen on the first board: WHITE: King (f1), Pawn (a6) BLACK: King (a8).

After 1. a6-A7 a8-B7 2. A7-a8 and promotes. The Black King was never on the right board to make a capture. Looks like a Pawn may be worth fifty percent more in the endgame. Variant Chess: Volume 6, Issue 42 is available on the web, with three games on pp 20-21 and the article "Paradoxical Endings in Alice Chess" on pp 28-29.

This is actually a common manoeuvre in checkmates with pieces that cannot triangulate (e.g. Knight + Camel). Often you cannot afford to triangulate with your King, because that would give the bare King the room to triangulate as well, thereby cancelling the effect. In Alice Chess no piece can truly triangulate, because they must alternate between the boards.

But I suppose there is a way around that when checkmating a bare King, as in that case it doesn't really matter on what board the King is: the bare King can never approach it without either moving into check or through it, both of which is forbidden. So you can treat it like the King is always on both boards.

WHITE TO MOVE AND MATE IN EIGHT MOVES

If the Bishop was on (f4), placing all the pieces on the same board, this would be a simple mate in two moves. But I needed help from ChessV to solve the given problem. Apparently the trick is to move the White King from (b3) to (C2), effectively "wasting a tempo". Bishops cannot do this in Alice Chess - while the Bishop could travel from (F4) to (f4) in three moves, that is not actually the same square. ChessV 2.2 game record is given below.

Alice Chess
Player(White) = ChessV
Player(Black) = Human
FENStart = "16/16/16/16/2N10B2/1K14/16/1k14 w - - 0 1"
StaticExchangeEvaluation = false
Moves = {
F4g5 b1A1 b3C2 A1a2 g5H6 a2A1 c4D6 A1a2 H6c1 a2A1 D6e4 A1a2 e4C3 a2A1 c1B2
}
Result = 1-0 {White wins}

This is a trial for using the Interactive Diagram for Alice Chess. Custom-supplied functions BadZone and WeirdPromotion take care of refusal of moves to squares of which the mirror square is occupied, and take care of shuttling the moved piece to the other board, respectively. The boards are separated by strip of 'hole' squares, which has to be two files wide to prevent Knights from crossing it.

I implemented e.p. capture as a move by the Pawn on the board where the doubly pushed Pawn started. This seemed the least illogical way to do it, as the e.p. square on that board will always be empty (or the double push would not have been allowed). And it is the square the double push really passed over, and thus where it could have been blocked. The move could still be illegal because the corresponding square on the other board is occupied, but that is normal for any move to an empty square in Alice Chess that would be legal on its own board. There has to be no extra rule to prevent double capture this way. This method of e.p. capture corresponds to one where the doubly pushed Pawn must first make a single retrograde step before being captured, rather than replacing its double step by a single step. That this is not the same is the fault of an Alice double push not really being two consecutive single pushes.

I still have a comment to make about the legality of moves (an aspect that the diagram doesn't address). The ambiguity here seems to be caused by not making proper distinction between legal and pseudo-legal moves, but heaping them all under the term 'legal'. A more precise description would have said that a move in Alice Chess is pseudo-legal if (before transfer) it would have been pseudo-legal in orthodox Chess on the board where it is made, and the target square on the other board is empty. And then an Alice move is legal (as usual) when it does not expose the King to pseudo-legal Alice capture. This prevents solving distant checks by interposing a piece that was on the board where the checked King resides (but then disappearing to the other board, so that the King can be captured) from being considered legal. Despite the fact that they would have been perfectly legal orthodox Chess moves on the board with the King.