How to play Four in a Row
Two sides take turns dropping discs into an upright grid of seven columns and six rows. Each disc falls to the lowest free slot in its column. Line up four of yours across, down or diagonally and you win.
Play the computer on Easy, Medium or Hard, or a coworker on the same screen. Against the computer you always drop the first disc, and a quick win scores more than a slow one.
Rules
- Each side has 21 discs, enough between them to fill the board. Your discs are solid, the other side’s are striped inside a ring, so the two never depend on colour.
- Four of one side in a line, across, down or along either diagonal, wins at once, and the four are marked on the board. If all 42 slots fill with no line, the game is a draw. A full column takes no more discs.
- A win against the computer scores 100, plus 100 for each of your 21 discs you didn’t need: winning with your 7th disc scores 1,500. Losses, draws and resignations score nothing. Each level keeps its own scores, stats and win streak. On Medium the Expert level is 300 and the Pro level 900.
- Easy looks two discs ahead and plays a random column about one move in three, so it misses wins and blocks. Medium looks five discs ahead. Hard keeps searching deeper until it has weighed 600,000 positions. Medium and Hard always take a win that is there and always block yours.
- In two-player games Player 1 has the solid discs and Player 2 the striped ones, and whoever went second starts the next game. Two-player games aren’t scored.
- Each level, and the two-player board, keeps its own game in progress, so switching tabs or closing the page loses nothing. Resigning a game against the computer counts as a loss.
Controls
- Click / tap a column
- Drop a disc into it
- ← → / A D
- Move the waiting disc over the columns
- Enter / Space / ↓
- Drop it; after a game, start the next
- 1 – 7
- Drop straight into that column
- N
- New game (against the computer, mid-game: resign)
Tips
- Take the centre column early. A disc there can be part of more lines of four than a disc anywhere else.
- Before every drop, check two things: can either side win right now, and does your disc open the slot above it for the other side?
- Aim for two threats at once. One open three gets blocked; two that need different slots can’t both be.
Four in a Row strategy
Odd rows and even rows
Number the rows 1 to 6 from the bottom. Late in a game the columns fill up and someone is forced to drop a disc under the other side’s threat. Counted through to the end, the first player tends to get the odd rows and the second player the even ones, so if you moved first (you always do against the computer), a threat whose empty slot is on row 3 or 5 is worth far more than one on row 2 or 4. The computer weighs its threats the same way.
Stack your threats
A threat is three of yours with the fourth slot empty. The computer blocks any threat it can reach right away, so build threats whose slot isn’t playable yet, or two that are playable at once. Best of all are two of your threats one above the other in the same column: once the lower slot is filled, whoever fills it, the upper one wins for you.
Every disc opens a door
Each disc you drop makes the slot above it playable. If the other side would win in that slot, the column is poisoned for you until something changes. Near the end, count the safe columns each side has left: the side that runs out first has to open a door.
How the levels think
Easy looks two discs ahead and drops into a random column about one move in three, even past a win or a block. Medium looks five discs ahead and picks at random among moves within a whisker of its best, so its games vary. Hard deepens its search until it has weighed 600,000 positions, which typically reaches eight to sixteen discs ahead (deepest in the opening), and stops early once it finds a forced result. It never misses a win or a block, but in the middle game it judges positions by counting open lines and threats, so a long plan built on row parity can still catch it.
About Four in a Row
Milton Bradley first sold this game as Connect Four in 1974, and four in a row on an upright grid of falling discs has been a fixture of toy shops and pub tables ever since. This is our own version, on the standard 7 × 6 board, under a generic name.
It is also a solved game. In 1988 James Dow Allen and, independently, Victor Allis showed that the first player can force a win by starting in the middle column. Nobody plays that perfectly in a coffee break, and neither does the Hard computer, but it punishes most slips.
Questions
Who wins with perfect play?
The first player, by starting in the centre column. James Dow Allen and Victor Allis each proved it in 1988. Start anywhere else and the second player can hold at least a draw.
Can the computer be beaten on Hard?
Yes. It sees every short trap but judges the middle game by counting open lines and threats, so patient play that builds threats on the right rows can beat it. Quick wins against it are rare, which is why its Expert and Pro levels are lower than on Easy.
How is the score worked out?
A win scores 100, plus 100 for each of your 21 discs you didn’t need. Winning with your 4th disc, the quickest possible, scores 1,800; winning with your last scores 100. Losses and draws score nothing.
Why are the discs striped?
So the two sides differ by pattern, not only by colour: yours are solid, the other side’s are hatched inside a ring. Nothing depends on telling the colours apart.
