(define "Line3D" 
    (!= 0 
        (count Sites
            in:(forEach 
                (expand (sites Bottom) steps:(- <Board:size> 1))
                if:(all Sites <Board:3dSites>
                    if:(= (mover) (who at:(site)))
                )
            )
        )
    )
)

//------------------------------------------------------------------------------

(game "3D Tic-Tac-Toe"
    (players 2)
    (equipment {
        (board (rectangle (+ (^ <Board:size> 2) (- <Board:size> 1)) <Board:size>))
        (piece "Disc" P1)
        (piece "Cross" P2)
        (piece "Dot" Neutral)
    })
    (rules
        (start (place "Dot0" <Board:dot0>)) // Places neutral dots to separate the four levels of the board.
        (play (move Add (to (sites Empty))))
        (end {
            (if (is Line <Board:size>) (result Mover Win))
            (if "Line3D" (result Mover Win))
        })
    )
)

//------------------------------------------------------------------------------

(option "Board Size" <Board> args:{ <size> <dot0> <3dSites>} {
    (item "3x3x3" 
        <3> 
        <(union {(sites Row 3) (sites Row 7)})> 
        <(sites {(site) (ahead (site) steps:4 N) (ahead (site) steps:8 N)})>
        "The game is played on a 3x3x3 board."
    )* 
    (item "4x4x4x4" 
        <4> 
        <(union {(sites Row 4) (sites Row 9) (sites Row 14)})> 
        <(sites {(site) (ahead (site) steps:5 N) (ahead (site) steps:10 N) (ahead (site) steps:15 N)})>
        "The game is played on a 4x4x4 board."
    ) 
})

//------------------------------------------------------------------------------

(metadata
    (info
        {
        (description "Tic-Tac-Toe on a nxnxn grid")
        (aliases {"Qubic"})
        (rules "Play occurs on a 4x4x4 grid. One player places an X, the other places an O and players take turns placing their marks in the grid, attempting to get four in a row of their color. For the lines between levels, the diagonals are not taken in account.")
        (id "1391")
        (source "<a href=\"https://boardgamegeek.com/boardgame/16387/3d-tic-tac-toe\" target=\"_blank\" class=\"style1\" style=\"color: #0000EE\" />BGG</a>")
        (version "1.3.12")
        (classification "board/space/line")
        (author "Woodrow Arthur Heacock, Herbert B. Swift, William Spyker")
        (credit "Ben Ritter")
        (date "23-08-1941")
        }
    )
    (graphics (piece Scale "Dot" 0.333))
    (ai
        "3D Tic-Tac-Toe_ai"
    )
)