Connect Four

How a Move Works

You choose a column, not a square. The disc falls to the lowest empty cell in that column, and where it comes to rest is not up to you — that is the whole character of the game. Red plays first, then the players alternate. The aim is four of your discs in an unbroken line: across a row, up a column, or along either diagonal. The first player to make one wins immediately. A column that is full cannot be played into, and if every column fills with nobody having made four, the game is a draw.

Why It Always Ends

Connect Four cannot go on forever, and this is worth noticing because most board games need a rule to guarantee it. Chess has the fifty-move rule; checkers needs something similar. Connect Four needs nothing: every move fills a cell, no cell is ever emptied, and there are only forty-two of them. Whatever either player does, the game is over within forty-two moves. There are no repeated positions to detect, because a position can never repeat.

Take the Middle

The centre column is on more four-in-a-row lines than any other — every horizontal line through the middle, the long diagonals, and its own column. A disc there is doing more work than the same disc on the edge, and the edge columns are on the fewest lines of all. This is why the solved opening is the centre, and it is also the most useful single habit for a beginner: when nothing obvious is happening, play towards the middle.

The Double Threat

Blocking works exactly once per turn. So the way games are actually won is by making two threats at the same time: a position where you have two different cells that would each complete a four. Your opponent blocks one, you play the other. Almost every Connect Four loss between competent players is this — not a four that was missed, but a fork that was allowed. An open three, with a playable cell at both ends, is the standard shape.

Never Fill the Cell Beneath a Threat

Gravity means a threat only matters once the cell beneath it is occupied. This cuts both ways and is where most beginners lose games without understanding why. If your opponent has a winning cell one row up, playing directly beneath it hands them the win — you build their staircase. Strong players count parity for exactly this reason: on a standard board the columns have an even height, so whose turn it is when a column reaches a critical row is often decided many moves earlier.