Всем известная игра в крестики нолики
Цель игры - построить непрерывный ряд из 5 крестиков по горизонтали, вертикали или диагонали.

                        
<script type="text/javascript">

 var TOTLIN, ATFAC, PLAYER, OPPON, IGROK, PROGR, WINLINE, GAMEEND;

 var IGT, X, Y, LX, LY, OTMENA=false;

 var BOARD, VALUE, LINP, WEIGHT = new Array(0, 0, 4, 20, 100, 500, 0);

 function sgn(T) { 

   if (T<0) T=-1; 

   else if (T>0) T=1; 

   else T=0;

   return T; 

  }

 function INICIAL() {

   var I, J, tr; 

   var f = '<table id="f" style="border: none; border-collapse:collapse;">'; 

   BOARD = new Array(); 

   VALUE = new Array(); 

   LINP = new Array();

   for (I=0;I<=20;I++) {

     if (I>0 && I<20) tr='<tr>';

     BOARD[I] = new Array();

     VALUE[I] = new Array();

     LINP[I] = new Array();

     for (J=0; J<=20; J++) {

       if (I*J>0 && I<20 && J<20) tr += '<td id="c-'+I+'-'+J+'" onclick="ANAKEY(this);" style="font-family: Tahoma, Helvetica, Sans Serif; border: 1px dotted #00a; cursor: pointer; width: 20px; font-weight: bold; text-align: center; vertical-align: middle; font-size: 16px; line-height: 20px">&nbsp;</td>';

       VALUE[I][J] = new Array();

       LINP[I][J] = new Array();

       for(C=1;C<3;C++) { LINP[I][J][C] = new Array(); }

      } 

     if (I>0 && I<20) { tr += '</tr>'; f += tr; }

    } 

   f += '</table>'; 

   document.write(f); 

   PROGR=0; 

   IGROK=0;

  }

 function ANAKEY(a) {

   X = a.id.replace(/c-/,'').replace(/-.*/,'');

   Y = a.id.replace(/c-/,'').replace(/.*-/,'');

   if (BOARD[X][Y] == 0) { 

     BOARD[X][Y]=1; MOVEXOD();

     if (GAMEEND) {

       IGROK += 1; 

       MESSAG('Поздравляем! Вы выиграли!');

      } 

     else {PRGMAK();} 

    }

  }

 function NEWGAME() { 

   var I, J, C, D; 

   if (OTMENA) { 

     alert('Игра не закончена!'); 

     return false; 

    }

   for(I=1;I<=19;I++) 

     for(J=1;J<=19;J++) { 

       geid('c-'+I+'-'+J).innerHTML='&nbsp;'; 

       geid('c-'+I+'-'+J).className=''; 

       BOARD[I][J]=0;

       for(C=1;C<3;C++) { 

         VALUE[I][J][C] = 0; 

         for(D=0;D<4;D++) LINP[I][J][C][D] = 0; 

        }

      } 

     geid('txt').innerHTML='Ваш ход'; 

     geid('prg').innerHTML=PROGR;

     geid('igr').innerHTML=IGROK; 

     PLAYER=1; 

     OTMENA=true; 

     TOTLIN=(19*(19-4)+(19-4)*(19-4))*4; LX=1; LY=1;

     X=10; 

     Y=X; 

     ATFAC=parseInt(IGROK/2); 

     if (ATFAC >15) ATFAC=15;

     for(I=1;I<20;I++) 

       for(J=1;J<20;J++) { 

         IGT = BOARD[I][J]; 

         DRAMOV(I,J);

        } 

  }

 function DRAMOV(XX, YY) {

   var idt; 

   LX=XX; 

   LY=YY; 

   idt='c-'+XX+'-'+YY;

   if (IGT == 1) {

     geid(idt).innerHTML='x';

    } 

   else if (IGT == 2) { 

     geid(idt).className='red'; 

     geid(idt).innerHTML='o';

    } 

  }

 function MOVEXOD() { 

   var T, K, L, X1, Y1, X11, Y11, DX, DY, NUM, LIO, LIP, TTT, idt;

   WINLINE = 0; 

   OPPON = 3 - PLAYER; 

   GAMEEND = false; 

   idt='c-'+LX+'-'+LY; geid(idt).className='';

   for (T=0;T<4;T++) 

     for(K=0;K<5;K++) { 

       X1 = parseInt(X) + sgn(T - 2) * K; 

       Y1 = Y - sgn(T) * K;

       switch(T) {

          case 0: TTT = X1 > 0 && X1 < 16; break;

          case 1: TTT = (X1 > 0 && X1 < 16) && (Y1 > 0 & Y1 < 16); break;

          case 2: TTT = Y1 > 0 && Y1 < 16; break;

          case 3: TTT = (X1 > 4 && X1 < 20) && (Y1 > 0 && Y1 < 16); break;

          default:;

         } 

       if(TTT) {

         NUM = LINP[X1][Y1][PLAYER][T]; 

         NUM = NUM + 1;

         if (NUM == 1) TOTLIN--; 

         else if (NUM == 5) GAMEEND = true;

         LINP[X1][Y1][PLAYER][T] = NUM; 

         if (GAMEEND && (WINLINE == 0)) WINLINE = T + 1;

         LIP = LINP[X1][Y1][PLAYER][T]; 

         LIO = LINP[X1][Y1][OPPON][T];

         for(L=0;L<5;L++) { 

           X11 = X1 - sgn(T - 2) * L; 

           Y11 = parseInt(Y1) + sgn(T) * L;

           if (LIO == 0) VALUE[X11][Y11][PLAYER]=VALUE[X11][Y11][PLAYER] + WEIGHT[LIP + 1] - WEIGHT[LIP];

           else

             if (LIP == 1) VALUE[X11][Y11][OPPON] = VALUE[X11][Y11][OPPON] - WEIGHT[LIO + 1];

          } 

        } 

      } 

   BOARD[X][Y] = PLAYER; 

   IGT = PLAYER;

   if (GAMEEND) {

      switch(WINLINE) {

         case 1: DX = 1; DY = 0; break; case 2: DX = 1; DY = 1; break;

         case 3: DX = 0; DY = 1; break; case 4: DX = -1; DY = 1; break;

         default:;

        }

      do { 

          X = (X - 0 + DX); 

          Y = (Y - 0 + DY); 

          } 

      while (BOARD[X][Y] == PLAYER); 

      X -= DX; 

      Y -= DY;

      for(I=1;I<6;I++) { 

        idt='c-'+X+'-'+Y; geid(idt).className='green'; 

        DRAMOV (X, Y); X = X - DX; Y = Y - DY; 

       }

    } 

   else { 

     DRAMOV (X, Y);

     PLAYER = OPPON; 

    } 

  }

 function PRGMAK() { 

   var I, J, MAX, VALZ;

   if (TOTLIN <= 0) { GAMEEND = true; MESSAG('Tie game!'); } 

   else {

     OPPON = 3 - PLAYER; 

     MAX = -32767; 

     X = 10; 

     Y = 10; 

     if (BOARD[X][Y] == 0) MAX = 4;

     for(I=1;I<20;I++) 

       for(J=1;J<20;J++) {

         if (BOARD[I][J]==0) { 

           VALZ=parseInt(VALUE[I][J][PLAYER]*(16+ATFAC)/16)+VALUE[I][J][OPPON]+parseInt(Math.random()*4);

           if (VALZ>MAX) {

             X = I; Y = J; 

             MAX = VALZ; 

            } 

          } 

        }

       MOVEXOD(); 

       if (GAMEEND) { 

         PROGR++; MESSAG('Компьютер победил!'); 

        } 

    } 

  }

 function MESSAG(SS) { alert(SS); OTMENA=false; NEWGAME(); }

 function geid(i) { return document.getElementById(i); }

</script>