How to play Connect Four

Connect Four is the beloved drop-and-stack game, played here against a computer opponent with nothing to download. The board stands upright: seven columns wide and six rows tall. You and the bot take turns dropping discs into the columns, and because of gravity each disc settles on top of whatever is already there. The first to build a line of four of their own discs wins. It is quick, it is tense, and a single careless drop can lose the game.

The goal

Connect four of your discs in an unbroken line — horizontally along a row, vertically up a column, or diagonally in either direction. If the whole board fills with no line of four, the game is a draw.

How to play

• Click or tap a column to drop your disc into it. You cannot choose the row — the disc falls to the lowest empty slot.
• The bot answers with a drop of its own, then it is your turn again.
• The winning four are highlighted the instant a line is completed.
• Your win, loss, and draw record is saved on this device, and you can let the bot move first if you want a tougher challenge.

Choose your difficulty

The bot uses a look-ahead search, and the difficulty levels control how deep it reads. Easy looks two moves ahead, Medium four, and Hard a full six moves ahead, which thinks for a moment longer but plays a sharp game. The bot is not mathematically perfect, but it spots threats reliably and will punish a loose move.

Strategy

The centre column is the strongest place to play — it takes part in more possible four-in-a-rows than any other column, so claim it early. Always scan for two things before you drop: can you make four this turn, and can your opponent make four next turn if you do not block them? The real skill is building a "double threat", two ways to win at once that the bot cannot both stop. Beware of setting up a winning square for the bot directly beneath where you want to play — every disc you drop becomes a platform for the next one.