Katy's Noughts and Crosses Game

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To win my game of noughts and crosses you need to have three X in a row before I get three O in a row. Click on the board in the place you want to put your X
When the game ends, you can start a new one by clicking anywhere on the board.

To make it more fun you can select any one of my four different levels of difficulty – Good luck, I will be watching to see how you are doing! The more you play the better you will get.




level 0 -- Katy in tired and distracted mode.
level 1 -- Katy in normal mode.
level 2 -- Katy in relaxed and confident mode you can win but only if you start.
level 3 -- Katy in genius mode, you may win, but you must follow the 3 steps below

(Step 1) You must have either won the previous game of any level, or have reset the game by pressing "F5" function key on on the top row of your keyboard, which forces me to let you start the game!

(Step 2) You must place your "X" in the centre square as your starting move, any other position you will loose.

(Step 3) Think very carefully before placing you "X's" try to anticipate what might be my next move each time, It might help to have a piece of paper and a pencil to help you to think ahead, don't rush and  Good Luck!


Despite the apparent simplicity of noughts and crosses, it requires some complex mathematics to determine the number of possible games. This is further complicated by the definitions used when setting the conditions.

In theory, there are 19,683 possible board layouts (39 since each of the nine spaces can be X, O or blank), and 362,880 (i.e. 9!) different sequences for placing the X’s and O’s on the board; that is, without taking into consideration winning combinations which would make many of them unreachable in an actual game.

When winning combinations are considered, there are 255,168 possible games. Assuming that “X” (That’s you) makes the first move every time:

131,184 finished games are won by ” X”
1,440 are won by “X” after 5 moves
47,952 are won by “X” after 7 moves
81,792 are won by “X” after 9 moves
77,904 finished games are won by “O”
5,328 are won by “O” after 6 moves
72,576 are won by “O” after 8 moves
46,080 finished games are drawn

Ignoring the sequence of X’s and O’s, and after eliminating symmetrical outcomes (i.e. rotations and/or reflections of other outcomes), there are only 138 unique outcomes. Assuming once again that “X” makes the first move every time:

91 unique outcomes are won by “X”
21 won by “X” after 5 moves
58 won by “X” after 7 moves
12 won by “X” after 9 moves
44 unique outcomes are won by “O”
21 won by “O” after 6 moves
23 won by “O” after 8 moves
3 unique outcomes are drawn

Strategy

You can play perfect noughts and crosses if you choose the move with the highest priority in the following.

Win: If you have two in a row, play the third to get three in a row.
Block: If the opponent has two in a row, play the third to block them.
Fork: Create an opportunity where you can win in two ways.

Block Opponent's Fork.

Option 1: Create two in a row to force the opponent into defending, as long as it doesn't result in them creating a fork or winning.
For example, if "X" has a corner, "O" has the centre, and "X" has the opposite corner as well, "O" must not play a corner in order to win. (Playing a corner in this scenario creates a fork for "X" to win.)

Option 2: If there is a configuration where the opponent can fork, block that fork.

Centre: Play the centre.
Opposite Corner: If the opponent is in the corner, play the opposite corner.
Empty Corner: Play in a corner square.
Empty Side: Play in a middle square on any of the 4 sides.

The first player, you or "X," has 3 possible positions to mark during the first turn. Superficially, it might seem that there are 9 possible positions, corresponding to the 9 squares in the grid. However, by rotating the board, you will find that in the first turn, every corner mark is strategically equivalent to every other corner mark. The same is true of every edge mark. For strategy purposes, there are therefore only three possible first marks: corner, edge, or centre. Player “X” can win or force a draw from any of these starting marks; however, playing the corner gives the opponent the smallest choice of squares which must be played to avoid losing.

The second player, me or "O," must respond to X's opening mark in such a way as to avoid the forced win. Player ” O” must always respond to a corner opening with a centre mark, and to a centre opening with a corner mark. An edge opening must be answered either with a centre mark, a corner mark next to the “X”, or an edge mark opposite the “X”. Any other responses will allow “X” to force the win. Once the opening is completed, O's task is to follow the above list of priorities in order to force the draw, or else to gain a win if “X” makes a weak play.

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