Connect 4: strategy

Play the centre

The middle column is part of more possible fours than any other: a disc there can join lines in every direction. Columns closer to the edge are worth less. The first player who takes the centre early is already ahead.

Think in threats

A threat is a space that would complete four for you. A single threat is easy to block. Two threats at once usually win: your opponent can only block one.

Look for shapes that create two threats with one disc, for example three in a row with both ends open.

Watch what's below

You can only play a space once the space under it is filled. So a threat above an empty space isn't playable yet, but it also stops your opponent from playing in that column safely: whoever fills the space below gives the other one the threat.

• Odd and even rows: counting from the bottom, the player who moved first usually gets to claim threats on odd rows (1, 3, 5) at the end of the game; the second player gets even rows. Build threats on your rows.

Don't give away the space below

Before you play, check the space directly above your move. If your disc lets your opponent complete four there, pick another column.

Against the bot

The hard bot looks 7 moves ahead and never misses a direct threat. To beat it you need a double threat or a position where every move it makes hands you a win (the endgame odd/even fight).