(define "Nbors"
    (count Sites 
        in:(intersection 
            (sites Around #1) 
            (sites Occupied by:All) 
        )
    )
)

(define "Grow"
    (forEach Site (sites Board) 
        (if (and 
                (is Empty (to)) 
                (= 3 ("Nbors" (to)))
            ) 
            (add (piece "Disc") (to (to))) 
            (if (and 
                    (is Occupied (to)) 
                    (or (< ("Nbors" (to)) 2) (> ("Nbors" (to)) 3))
                ) 
                (remove (to)) 
            )
        )
    )
)

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

(game "Game of Life" 
    (players 0) 
    (equipment { 
        (board <Board>) 
        (piece "Disc" Shared) 
    }) 
    (rules 
        (start (place "Disc" (sites {<Start>}))) 
        (play 
            ("Grow")
        )
        (end (if (= (count Moves) 100) (result Mover Draw)))
    )
)

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

(option "Board" <Board> args:{ <board> } {
    (item "Square 8x8" <(square 8)> "Square 8x8 board.") 
    (item "Square 12x12" <(square 12)> "Square 12x12 board.")* 
    (item "Hex 5"  <(hex 5)> "Hex 5 board.") 
})

(option "Start" <Start> args:{ <start> } {
    (item "Glider"  
        <"B4" "C4" "D4" "D3" "C2">
        "Self-perpetuating glider pattern."
    )
    (item "Lightweight Spaceship"  
        <"C3" "D3" "E3" "F3" "B4" "F4" "F5" "C6" "E6">
        "Self-perpetuating Lightweight spaceship pattern."
    )*
    (item "Blinker"  
        <"B3" "C3" "D3">
        "Oscillating blinker pattern."
    )
    (item "Toad"  
        <"B3" "C3" "D3" "C4" "D4" "E4">
        "Oscillating toad pattern."
    )
    (item "Beacon"  
        <"B2" "C2" "B3" "C3" "D4" "E4" "D5" "E5">
        "Oscillating beacon pattern."
    )
    (item "Block"  
        <"B2" "C2" "B3" "C3">
        "Static block pattern."
    )
})

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

(metadata
    (info
        {
        (description "Board game version of Conway's Game of Life.")
        (rules "At each tick, a set of rules are applied to every board cell, which determine whether a piece 'lives' or 'dies' at each cell. Any live cell with two or three live neighbours survives.
            Any dead cell with three live neighbours becomes a live cell.
        All other live cells die in the next generation. Similarly, all other dead cells stay dead.")
        (id "708")
        (source "<a href=\"https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life\" target=\"_blank\" class=\"style1\" style=\"color: #0000EE\" />Wikipedia</a>")
        (version "1.3.14")
        (classification "simulation")
        (author "John Horton Conway")
        (credit "Eric Piette and Cameron Browne")
        (date "1970")
        }
    )
)