Tic Tac Toe Countdown

The typical time killer game " tic tac toe" will come out with new functions, makes you keep going for hours.
Basic rule is same as usual, Players alternate placing Xs and Os on the board until
either one player has three in a row, horizontally, vertically or diagonally.
But what this game is special is that the symbol you placed first will disappear when your forth turns come, so players will never result in tie.
Countdown until disappear will be shown upper right of each symbol.
You can choose whether or not to show the countdown number from the top page.