Chimp Four

Objective

Be the first to get four of your discs in a line — across, up and down, or diagonally. You play clay (the red-brown discs); your opponent plays slate (the blue ones). Each color is engraved with its own pattern, so you can always tell them apart at a glance.

How To Play Chimp Four

Chimp Four is also known as Captain's Mistress, Drop Four, Four in a Line, Four in a Row, Four Up, Gravitrips, and Plot Four.

Dropping a disc

Press anywhere on the board and slide left or right. A faded disc follows your finger to show where it will land. Let go to drop it.

Nothing falls until you release, so if you change your mind, just slide to a different column first — or slide right off the board to cancel the move entirely. A quick tap works too: that's simply a very short slide.

Discs fall to the lowest free space in the column, so you never choose the row, only the column. A full column can't take any more.

On a keyboard: arrow keys to choose a column, Enter or Space to drop. The number keys 1 to 7 drop straight into that column.

Taking turns

Clay and slate take turns, one disc each.

Whoever goes first alternates from game to game. Going first is a real advantage in this game, so neither side keeps it — if clay started the last game, slate starts the next one. The board tells you whose turn it is at the top.

Ways to play

Open the settings to choose:

Two players — pass the device back and forth.
You vs computer — you play clay, the computer plays slate.
Watch two computers — set a strength for each side and let them play it out. You can pause at any point, or step through one move at a time.

How strong is the computer?

Four settings, from Easy to Expert. Easy misses things and will let you win. Medium spots the obvious threats. Hard looks several moves ahead and punishes mistakes. Expert is genuinely difficult — it will beat most people most of the time, though it isn't perfect.

In "watch two computers" you can set each side separately, which is the fun way to see how much the difference actually matters.

Undo and the score

Undo takes back the last move. Playing the computer, it takes back both its move and yours, so it's your turn again.

The tally at the top counts wins for each color and draws, and it carries on across games. Restart replays the current game; when a game has finished the button becomes Next game. To clear the tally and start fresh, use Reset score in the settings.

If every square fills up and nobody has four in a line, the game is a draw.

A few tips

Play the middle. The centre column is part of more possible lines than any other, so a disc there is worth more than a disc on the edge. It's the strongest opening move.

Look at what you're building underneath them. Every disc you drop hands your opponent the square directly above it. Before you play, check whether that square completes a line for them.

Two threats beat one. A single row of three is easy to block. If you can set up two places where your fourth disc would win, your opponent can only block one of them.

Watch the diagonals. They're the easiest lines to miss — both yours and theirs. When you're scanning the board for danger, check the diagonals last and check them twice.

Contact: Feel free to contact us with any bugs, complaints, or requests.

Release Date: September 4, 2026

History

Ancient idea, modern game

Games about lining up pieces in a row are about as old as games get. Versions of noughts-and-crosses turn up in the ancient world, and the family tree spreads from there through morris games, gomoku and dozens of others.

What makes this particular game different is gravity. You don't place a piece wherever you like — you choose a column and let it fall. That single restriction changes everything: it shrinks your options, and it means every disc you play hands your opponent the square directly above it. That vertical, gravity-fed version is much younger than the line-up-four idea it's built on.

The Captain's Mistress

The story you'll hear most often is that the game is centuries old, and that Captain James Cook played it obsessively in his cabin on long voyages — so obsessively that his crew nicknamed it "the Captain's Mistress."

It's a lovely story. It's also almost certainly not true, or at least nobody has ever managed to show that it is. The primary records of Cook's voyages don't describe anything like it. One game historian who went looking couldn't confirm that the legend existed at all before modern game companies started printing it on boxes, let alone that it referred to a game that was vertical or about four in a row.

What kept the legend alive is commerce: wooden "Captain's Mistress" sets have been sold for decades, each one repeating the story on its packaging. It's a good reminder that a tale printed on enough boxes eventually starts sounding like history.

The near-misses

There are real ancestors, just less romantic ones.

The board game historian Robbie Bell documented a wooden game called Four Balls — mahogany, with beech balls dropped into runners — which he dated to roughly 1901 to 1910. That's a genuine gravity-fed four-in-a-row game from the Edwardian era, and it predates the modern version by seventy years.

There were others circling the same idea. A three-dimensional noughts-and-crosses was patented in 1946. A game called Score Four, played by stacking beads onto pegs, was sold in the late 1960s. The concept was clearly in the air.

1974

The version everyone knows was designed by two American game inventors, Howard Wexler and Ned Strongin, and licensed to the Milton Bradley Company, which first sold it under the Connect Four trademark in February 1974. It was a hit immediately and has never really stopped selling. Milton Bradley was acquired by Hasbro a decade later, and Hasbro owns it still.

Wexler has described the idea plainly: he noticed that games were played flat, on a horizontal surface, and wondered what would happen if a game stood up and was played on a vertical one. That's the whole invention, and it's a good one.

It's worth being precise about what is and isn't owned here. The rules of a game — drop a piece, get four in a line — aren't something anyone can own. The name and the specific look of a product are. That's why this game turns up under a long list of other names: Four in a Row, Four Up, Four in a Line, Drop Four, Plot Four, and, in the Soviet Union, Gravitrips.

The year it was solved

In October 1988, two people independently worked out the answer to the game.

James Dow Allen got there first, on the 1st. Victor Allis followed on the 16th, as part of a master's thesis at the Vrije Universiteit in Amsterdam built around what he called threat-based strategy. They reached the same conclusion by different routes: on a standard seven-by-six board, the player who moves first can always win — but only by opening in the centre column, and only by playing perfectly for the rest of the game.

The details are sharper than that summary suggests. Open in one of the two columns beside the centre and the best you can force is a draw. Open in any of the four outer columns and, with perfect play, you lose. The first move decides the whole game before either player has thought about anything.

In 1995 John Tromp went further and computed the value of every reachable position — roughly four and a half trillion of them. There is now nothing left to discover about who wins from where.

So why is it still fun?

Because nobody plays perfectly. The winning line runs dozens of moves deep and requires flawless calculation at every step; no human holds that in their head, and neither does the computer opponent in this game. "Solved" describes what a perfect player could do, not what happens when two imperfect ones sit down across a board.

What the solution does give you is one practical lesson, and it's the most useful thing in this whole page: going first is a genuine advantage, and the centre column is where that advantage lives.

Why Chimp Four alternates who starts

Because of everything above. If the same color always went first, one seat would carry a permanent, mathematically proven edge, and a long match would be decided by seating rather than skill.

So we alternate. If clay opened the last game, slate opens the next one. Over a match the advantage cancels out, and what's left is the part that was always the point — whether you saw the diagonal coming.