How to play tic tac toe.

How to play

1. 1X always goes first. Take turns putting your mark in any empty square.
2. 2Get three of your marks in a straight line across, down or diagonally, and you win.
3. 3Fill all nine squares with nobody getting a line and the game is a draw.

Strategy

• ·Grab the centre if it is open. Four of the eight winning lines run through it. A corner sits on three lines, an edge on only two.
• ·If you go second and your opponent takes the centre, answer in a corner. Reply on an edge and a good player will beat you.
• ·Watch for forks. One move that sets up two threats at once wins, because your opponent can only block one of them.

How to play

1. 1The big board holds nine small boards. Win a small board and that square of the big board becomes yours.
2. 2The square you pick inside a small board sends your opponent to the small board in that same position.
3. 3Get sent to a board that is already won or full and you can play anywhere you like.
4. 4Win three small boards in a row on the big board to take the game.

Strategy

• ·Think about where you are sending them, not just where you are playing. Winning a small board is a bad deal if it hands them the centre.
• ·Sending someone to a finished board gives them the run of the whole game. Only do it when the trade is clearly worth it.
• ·The centre board shows up in four of the eight big board lines, so it is worth more than any other.
• ·Giving up a small board on purpose is often right if it buys you the tempo to take two better ones.

How to play

1. 1Take turns placing marks anywhere on the 5x5 grid.
2. 2Four in a row across, down or diagonally wins.
3. 3A full board with nobody getting four is a draw, though you will rarely see one.

Strategy

• ·Play towards the middle. Central squares belong to far more four in a row lines than the edges do.
• ·Two in a row with both ends open beats three in a row that is already walled off. Count the space, not the stones.
• ·Check the diagonals. On this size of board they are what people miss.

How to play

1. 1Take turns placing marks anywhere on the 7x7 grid.
2. 2Five in a row in any direction wins.
3. 3If the board fills with no line, it is a draw.

Strategy

• ·An open three, meaning three in a row with both ends free, forces your opponent to respond. Set up two of them and the game is yours.
• ·Do not chase them square by square. Block in the spot that also builds something for you.
• ·Skip the corners. Almost no five length lines run through them.

How to play

1. 1Take turns placing stones on any empty point of the 15x15 grid.
2. 2First to five in a row across, down or diagonally wins.
3. 3A full board with no five is a draw. In real games this basically never happens.

Strategy

• ·Learn the shapes. An open three has to be answered. An open four has already won.
• ·A double three, where one stone creates two open threes, beats almost every defence.
• ·Keep your stones close together. Scattered stones threaten nothing. Stones within two squares of each other threaten plenty.
• ·Going second means defending first. Block early instead of trying to race.

How to play

1. 1Take turns placing marks the same way you would in a normal game.
2. 2Making three of your own marks in a row loses on the spot.
3. 3Fill the board with neither player making a line and it is a draw.

Strategy

• ·The centre is now the worst square on the board. It sits on four lines you are trying not to finish.
• ·Stop thinking about the squares you want. Think about the squares you are forcing them into.
• ·Late in the game, count the empty squares. Parity decides who runs out of safe moves first.

How to play

1. 1On your turn, place either an X or an O in any empty square.
2. 2Whoever completes three in a row wins, no matter which mark the line is made of.
3. 3A full board with no line is a draw.

Strategy

• ·You are never blocking a player, only a line. Any two in a row of either symbol is a live threat.
• ·Putting down a mark that helps a line you cannot finish next turn usually just gifts it to them.
• ·Mirroring across the centre keeps things level while you hunt for a fork.

How to play

1. 1Both players place an X. There are no O marks anywhere in this game.
2. 2The player who completes three Xs in a row loses immediately.
3. 3Because both players use the same mark, draws are impossible. Somebody always runs out of safe squares.

Strategy

• ·Stop hunting for lines and start counting safe squares. The only question is who runs out first.
• ·Opening in the centre is the strongest first move on a single board.
• ·Remember that every X you place is an X your opponent gets to use too.

How to play

1. 1The odd player holds 1, 3, 5, 7 and 9 and moves first. The even player holds 2, 4, 6 and 8.
2. 2On your turn put one of your remaining numbers in any empty square. Each number gets used once.
3. 3Complete a row, column or diagonal that adds to exactly 15 and you win, whoever placed the other two numbers.
4. 4Fill all nine squares without a line of 15 and it is a draw.

Strategy

• ·The 5 is the strongest number on the board. In the magic square it sits dead centre, part of every line that reaches 15.
• ·Keep track of what your opponent has left. A threat is empty if the number they need is already spent.
• ·Watch lines you did not start. You can win on a line where they placed two of the three numbers.

How to play

1. 1Order moves first. On your turn place either an X or an O in any empty square. Both players get to use both symbols.
2. 2Order wins as soon as five of the same symbol sit in a row, column or diagonal, regardless of who placed them.
3. 3Chaos wins if the board fills up and no such line exists.
4. 4Exactly five counts, and so does any longer run that contains five.

Strategy

• ·Playing Chaos, never place the symbol that finishes a threat. Place the other one. Same square, opposite result.
• ·Playing Order, build two threats at once. Chaos can only poison one square per turn.
• ·Playing Order, work near the middle. A corner belongs to far fewer five length windows than a central square.
• ·Playing Chaos, mix symbols inside the same window. One X and one O in the same five squares kills that window for good.

How to play

1. 1On your turn pick two different empty squares. Your mark goes into both, tagged with the move number. It is in neither square yet, and in both.
2. 2Squares and marks form a network. When your pair closes a loop in that network, the loop has to be measured.
3. 3Your opponent does the measuring. They choose which of its two squares your looping mark takes, and every other mark in the loop is then forced into whatever square is left for it.
4. 4Measured marks become real and their squares close for good. Three real marks in a row wins.
5. 5If one measurement gives both players a line, the win goes to whoever’s line has the lower highest tag, meaning the one that settled first.

Strategy

• ·Closing a loop hands your opponent the choice of how it resolves. Only close one when both outcomes suit you.
• ·A mark spread across two far apart squares is hard to pin down. Two marks sharing the same pair of squares are almost decided already.
• ·Tags break ties, so an early mark inside a line is worth more than a late one.
• ·Count the loop before you commit. One running through five squares rearranges far more of the board than one through two.

How to play

1. 1The board is four stacked 4x4 levels, shown side by side.
2. 2Place your mark in any empty cell on any level.
3. 3Four in a row wins: inside a level, straight up through the levels, or along any diagonal, including the four that cut through the whole cube.
4. 4There are 76 winning lines in total.

Strategy

• ·The eight cells nearest the middle of the cube sit on the most lines. Fight for those first.
• ·Check straight up every single turn. Vertical columns are the threat people miss most.
• ·Corners of the cube belong to seven lines each, far more than a corner on a flat board.