Gomoku game in Mathematica.

Gomoku.nb

DynamicModule[{board, winner, p, pmouse, ppossible, v, Reset}, 
 Reset[] := {winner, board} = {"", ConstantArray[0, {20, 20}]}; 
 Reset[]; Deploy@
  Graphics[Button[{Brown, Rectangle[{0, 0}, {20, 20}], Black, 
     Line[Join @@ 
       Table[{{{i, 0}, {i, 20}}, {{0, i}, {20, i}}}, {i, .5, 19.5}]], 
     Dynamic[pmouse = 
       Ceiling@MousePosition["Graphics", {-1, -1}] /. {0 -> 1, 
         21 -> 20}; 
      If[1 <= Min@pmouse <= Max@pmouse <= 20 && 
        winner == "", {Opacity@.3, Disk[pmouse - .5, .4]}, {}]], 
     Dynamic[Disk[# - .5, .4] & /@ Position[board, 1]], White, 
     Dynamic[Disk[# - .5, .4] & /@ Position[board, -1]], Red, 
     Text[Style[Dynamic@winner, 60], {10, 10}]}, 
    If[winner != "", Reset[], p = pmouse; 
     If[Extract[board, p] == 0, board[[p[[1]], p[[2]]]] = 1; 
      FinishDynamic[]; 
      If[Max[Table[
          Total[RotateRight[board, #*d] & /@ 
            Range[0, 4]], {d, {{0, 1}, {1, 0}, {1, 1}, {1, -1}}}]] == 
        5, winner = "You win!", ppossible = Position[board, 0]; 
       v = (9*^9 Count[#, {___, -1, -1, -1, -1, ___}] + 
            3*^8 Count[#, {___, 1, 1, 1, 1, ___}] + 
            1*^7 Count[#, {___, 0, -1, -1, -1, 0, ___}] + 
            5*^5 Count[#, {___, 0, 1, 1, 1, 0, ___}] + 
            3*^5 Count[#, {___, 0, -1, -1, -1, ___}] + 
            3*^5 Count[#, {___, -1, 0, -1, -1, ___}] + 
            3*^5 Count[#, {___, -1, -1, 0, -1, ___}] + 
            3*^5 Count[#, {___, -1, -1, -1, 0, ___}] + 
            2*^4 Count[#, {__, 0, -1, -1, 0, __}] + 
            2*^4 Count[#, {__, 0, -1, -1, 0, __}] + 
            2*^4 Count[#, {__, 0, 0, -1, -1, 0}] + 
            2*^4 Count[#, {0, -1, -1, 0, 0, __}] + 
            2*^4 Count[#, {___, 0, -1, 0, -1, 0, ___}] + 
            2*^3 Count[#, {___, 0, 1, 1, 1, ___}] + 
            2*^3 Count[#, {___, 1, 0, 1, 1, ___}] + 
            2*^3 Count[#, {___, 1, 1, 0, 1, ___}] + 
            2*^3 Count[#, {___, 1, 1, 1, 0, ___}] + 
            2*^3 Count[#, {__, 0, 1, 1, 0, __}] + 
            2*^3 Count[#, {__, 0, 1, 1, 0, __}] + 
            2*^3 Count[#, {__, 0, 0, 1, 1, 0}] + 
            2*^3 Count[#, {0, 1, 1, 0, 0, __}] + 
            2*^3 Count[#, {___, 0, 1, 0, 1, 0, ___}] + 
            100 Count[#, {_, __, 0, -1, 0, __, _}] + 
            100 Count[#, {__, 0, 0, -1, 0, _}] + 
            100 Count[#, {_, 0, -1, 0, 0, __}] + 
            50 Count[#, {_, __, 0, 1, 0, __, _}] + 
            50 Count[#, {__, 0, 0, 1, 0, _}] + 
            50 Count[#, {_, 0, 1, 0, 0, __}]) & /@ (Table[
             Extract[board, 
              Mod[# + n*d, 20, 
               1]], {d, {{0, 1}, {1, 0}, {1, 1}, {1, -1}}}, {n, 
              Delete[Range[-4, 4], 5]}] & /@ ppossible); 
       p = RandomChoice@Extract[ppossible, Position[v, Max@v]]; 
       board[[p[[1]], p[[2]]]] = -1; 
       If[Min[Table[
           Total[RotateRight[board, #*d] & /@ 
             Range[0, 4]], {d, {{0, 1}, {1, 0}, {1, 
              1}, {1, -1}}}]] == -5, winner = "You lost!"]]]]], 
   Background -> Lighter[Brown, .1], ImageSize -> 419]]