Connect 4 strategy
Connect 4 looks like a game of spotting lines. It is a game of controlling squares. Here is how strong players think about it, from the first drop to the last. New to the game? Start with the rules.
Take the centre column
There are 69 possible lines of four on the board, and more of them pass through the centre column than any other. A disc in the middle takes part in up to 13 winning lines; a disc on the edge, only 3. With perfect play the first player wins by opening in the centre and only in the centre: the two columns beside it draw, and anything further out loses.
So: first move in the middle, and when you have no better idea later on, play as centrally as you can.
Think in threats, not lines
A threat is an empty square that would complete four for you. Three discs in a row with an open end is a threat; so is a gap in the middle of your line. Beginners try to complete lines. Strong players count threats, because a threat does not have to be cashed in now: it sits on the board, and eventually your opponent will be forced to play beneath it and hand it to you. Every move, ask two questions: which squares are threats for me, and which are threats for them?
Build double threats
A single threat gets blocked. The winning pattern is creating two at once, so your opponent can only block one of them. Here red has three in a row with both ends open: whatever blue does, red wins next turn. The daily puzzle on Find Four is this idea in its purest form, one move that creates two winning squares.
The strongest double threats stack: two of your threats in the same column, one directly above the other. Your opponent can never block the lower one without giving you the upper one.
Watch the diagonals
Most losses below intermediate level come from a missed diagonal. Rows and columns are easy to see; diagonals are built one disc at a time across several columns and are easy to lose track of. After every opponent move, trace both diagonals through the disc they just played. Blue is one drop from winning here, and red, staring at the horizontal, might never see it.
Odd and even rows
This is the rule that decides most endgames, and most players have never heard it. Number the rows from the bottom: 1, 2, 3, 4, 5, 6. Because players alternate and columns fill from the bottom, when the board gets crowded the first player tends to end up playing on the odd rows and the second player on the even rows.
So a threat is only as good as its row. As the first player (red), a threat on row 3 or row 5 is gold: sooner or later your opponent will be forced to fill the square beneath it. A threat on row 4 is usually worthless, because you will be the one forced to play under it. As the second player, it is the reverse: build your threats on even rows. When both players have a threat in the same column, the lower one wins the game.
Don't hand over the winning square
Before you drop, look at the square directly above where your disc will land. Playing into a column raises its landing height by one, and if that new landing square is your opponent's threat, you have just handed them the game. Late in a game, most columns are poisoned this way for one player or the other, and the whole contest becomes a matter of who runs out of safe moves first.
Playing second: follow up
Going second is harder, since the first player has a theoretical forced win. But there is a simple plan that holds against anyone who is not playing perfectly: follow up. Whenever it is safe, play directly on top of your opponent's last disc. Doing so guarantees you the even-row squares in that column, which is exactly where your threats belong, and it denies the first player the odd squares they need. Break the pattern only to block an immediate win or to take one yourself.
Common mistakes
- Chasing your own three in a row when your opponent already has a line waiting one square away. Check their threats before extending yours.
- Playing on the edges early. Edge discs join far fewer lines than central ones, and edge columns are the ones you want to save for when everything else is poisoned.
- Blocking a threat by playing directly beneath it. That does not block anything, it fills the square that lets them play there next turn.
- Cashing a single threat too early. A threat on the right row is a weapon you hold; using it to win one disc's worth of tempo is a waste.
- Playing fast in a slow game. Bullet is for reflexes; in Rapid and Unlimited the winning move is usually the one you find after checking every column once.
Pop Out changes the maths
In Pop Out, a player can remove one of their own bottom discs and drop the whole column by one. The odd-even rule still matters, but a pop flips the parity of a column, so a "worthless" even-row threat can become live. Two habits win Pop Out games: keep your own discs on the bottom row where they give you options, and before every pop, check what the column looks like one square lower for both colours. A pop that completes your opponent's line loses on the spot.
How to practise
Play the computer on Medium until you win most games, then Hard. The bots are honest about how they lose, so when a game goes wrong you can usually point at the move. Solve the daily puzzle to train your eye for double threats, and browse the archive when you want more. Then take it to ranked, where a rating tells you honestly whether it is working.
Put it to the test
Start with the centre column. See how far it gets you.