How to play Four in a Row

The board stands upright: 7 columns, 6 rows. You and the computer take turns dropping a disc into a column, and it falls to the lowest empty square. The first to line up four of their own discs, across, up or on a diagonal, wins. If all 42 squares fill with no four, it is a draw.

Play Four in a Row

The rules

• Tap a column to drop your disc into it. A full column takes no more.
• A disc always lands on the one below it, so you can only claim the lowest empty square of a column.
• Four in a line wins at once, in any direction.

The levels

Choose a level from 1 to 6 and who goes first. Every level plays perfectly until 12 discs are on the board. After that:

• Level 1 gets about every other move wrong, and it can miss a four in a row.
• Level 2 gets about one move in three wrong, and it can miss a four in a row.
• Level 3 gets about one move in four wrong, but always takes or blocks a four in a row.
• Level 4 gets about one move in seven wrong, but always takes or blocks a four in a row.
• Level 5 gets about one move in fifteen wrong, but always takes or blocks a four in a row.
• Level 6 never makes a mistake.

The player who goes first can always win with perfect play, starting in the middle column. Going second against level 6, no game can be won.

The owl

The owl marks every column with what it leads to with best play from both sides: a win, a draw or a loss. When the game ends, it names the first move of yours that changed the result, and the column that would have kept the better one.

Strategy

• Block a four. When the computer has three in a line with the fourth square playable, that square comes first.
• Make two fours at once. Two winning squares side by side, or one directly above the other, cannot both be blocked.
• Don't play under a four. If the square above yours would complete a four for the computer, your disc hands it that square. Leave that column alone.
• Odd and even rows. Count rows from 1 at the bottom. As the columns fill, the first player's threats on odd rows and the second player's on even rows are the ones that come true, because the other side is forced to play under them.
• Take the middle. The centre column sits on more possible fours than any other.