Last updated: March 2026
What Is Connect 4?
Connect 4 (also written Connect Four) is a two-player strategy game played on a vertical 7-column, 6-row grid. Players take turns dropping colored discs into the board from above. Each disc falls to the lowest available position in the chosen column. The first player to line up four consecutive discs in any direction — horizontal, vertical, or diagonal — wins.
Originally patented by Milton Bradley in 1974 and designed by Howard Wexler, Connect 4 has become one of the best-selling two-player board games in history with over 50 million copies sold. It was mathematically solved in 1988 by Victor Allis, who proved the first player can always win with perfect play from the center column.
This online version includes three AI difficulty levels, disc drop animations, undo, score tracking, and a two-player mode. Play instantly in your browser with no signup or download required.
How to Play Connect 4
Choose your mode: vs AI (select Easy, Medium, or Hard) or vs Friend for same-device two-player games. Easy AI makes mostly random moves; Medium searches three moves ahead; Hard uses minimax with alpha-beta pruning at depth six.
Click or tap a column to drop your disc. A ghost preview shows where it will land. The disc falls with a smooth animation and bounces slightly at the bottom.
Line up four discs in a row to win. Winning discs pulse with a highlight effect. Use Undo to take back moves, or start a New Game while keeping your score.
Frequently Asked Questions
How do you win at Connect 4?
Control the center column — discs placed there participate in more potential four-in-a-row lines than any other position. Build threats in multiple directions simultaneously so your opponent can't block everything. Setting up a double threat (two ways to win at once) is the most reliable path to victory.
Can you always win Connect 4 if you go first?
Mathematically yes — the first player can force a win with perfect play by starting in the center column. This was proven by Victor Allis in 1988. In practice, perfect play requires calculating dozens of moves ahead, which is why the game remains fun and challenging for humans.
What is the best opening move in Connect 4?
Always drop your first disc in the center column. It participates in the highest number of potential four-in-a-row combinations — horizontal, vertical, and both diagonals. Starting anywhere else allows the second player to equalize with correct play.
Can two players play Connect 4 on the same device?
Yes — select the "vs Friend" mode. Players alternate turns on the same screen. The board displays whose turn it is and tracks both players' scores across multiple games. Player 1 is Red and goes first; Player 2 is Yellow.
How strong is the Hard AI?
The Hard AI uses minimax with alpha-beta pruning at depth 6, evaluating tens of thousands of positions per move. It blocks your wins, exploits double threats, and prioritizes the center column. It is beatable but requires planning several moves ahead.