Connect Four: choose a column, build a line

Understand the board before choosing a move

The grid has seven columns and six rows. Selecting a column with room places your piece in its lowest available square. You cannot choose a higher square while leaving an empty space underneath it. A full column cannot accept a seventh piece.

In the main mode, you play X against O, a local computer opponent. It replies after a valid move if the game is still active. This is not a connected multiplayer room or an invitation to wait for another person to respond from a different device.

Four pieces must form one uninterrupted line

A win requires four consecutive marks from the same side in a horizontal, vertical, or diagonal line. Four pieces scattered around the grid do not satisfy the rule. Diagonals can slope upward to the left or to the right, so scan both directions.

If all forty-two squares are occupied without a completed winning line, the game is a draw. No extra column appears and gravity does not change to break the tie. The result is based on the pieces that were actually placed, not on the number of promising threats either side imagined earlier.

A promising square has to be reachable

Imagine three Xs in a high row with a gap beside them. That gap is an immediate winning square only if the column below it already has enough pieces to support the next drop at that height. Without that support, choosing the column lands your piece lower down.

Check the landing point before calling a move a win. Pieces from either side can support a future threat. A move that does not create an obvious line may still change which rows become reachable on later turns. The geometry of the column matters as much as the attractive shape in the row.

Use three priorities before dropping

First, look for a column that completes four immediately. Count consecutive pieces and verify the landing square. A line interrupted by an opposing piece cannot be treated as an open path through that square.

Next, inspect O’s immediate winning drops. If you cannot win now, identify the column and height that actually stop the threat. Blocking a different square in the same column is not necessarily a block. Point to the missing square rather than relying on a general impression of danger.

Finally, compare the positions you leave for the following turn. Central columns participate in more possible lines, but that does not make them universally correct. A center move can supply the support for an opposing diagonal. A side column may be essential to prevent an immediate loss.

Know what the local computer does

The main opponent checks for an immediate win, blocks an immediate loss, then follows a column preference. It is not presented as a perfect solver of every possible position. Beating this opponent does not establish that the same fixed sequence will beat any person.

A useful strategy explanation states its conditions: whose turn it is, which pieces are present, which columns remain open, and where a piece will land. No short rule turns every position into a win. When a guide promises victory regardless of the reply, inspect whether it has left out a necessary board condition.

Choose a control and keep your place

On a phone, use the column controls. On a computer, navigate between columns and activate the selected one with the keyboard. Visible focus helps you inspect the destination before committing. You do not have to drag a small piece precisely into a particular grid square.

The browser stores the game locally, and Pause lets you step away. Progress is not synced to another device or published on a global ranking. Restart begins a fresh board after confirmation. For two people sharing one device, use the separate local mode that alternates both human turns rather than confusing it with this main computer-opponent mode.