Last updated: March 2026
What Is Connect Four?
Connect Four is a two-player strategy game where opponents take turns dropping colored discs into a vertical grid. The first to connect four discs horizontally, vertically, or diagonally wins. This free online version features an AI opponent with three difficulty levels powered by a minimax algorithm.
Originally released as a board game in 1974, Connect Four has been played by over 100 million people. The game is mathematically solved — the first player can force a win with perfect play — but the AI on Hard mode makes this extremely challenging.
How to Play
1. Choose vs AI or 2 Player mode, then select difficulty.
2. Click or tap a column to drop your disc.
3. Connect four in a row to win.
4. Use Undo to take back moves. Track your score across games.
Key Features
The AI uses minimax search with alpha-beta pruning, evaluating thousands of board positions to find optimal moves. Physics-based disc drop animations give the game a satisfying feel.
Frequently Asked Questions
Is Connect Four free to play online?
Yes — this Connect Four game runs entirely in your browser. No download, no signup, no ads. Just click Start and play immediately against the AI or a friend.
How many difficulty levels are there?
Three levels: Easy (makes occasional mistakes), Medium (plays well using minimax search), and Hard (extremely challenging with deep alpha-beta pruning). Even experienced players find Hard mode very difficult.
Can two people play on the same device?
Yes — select '2 Player Local' mode to take turns on the same screen. Player 1 uses red discs and Player 2 uses yellow.
What is the best strategy for Connect Four?
Control the center column — it's part of more possible four-in-a-row combinations than any edge column. Build threats in multiple directions so your opponent can't block both. The first player has a mathematical advantage with perfect play.
Does it keep score across games?
Yes — wins for Red, wins for Yellow, and draws are tracked throughout your session. Click New Game to play again without losing your score history.