Connect Four - Online PvP & AI Board Game

Players take turns dropping colored discs into a 7-column, 6-row vertical grid. The first player to connect four of their discs in a row—horizontally, vertically, or diagonally—wins. Click any column indicator above the board or tap a column on mobile to drop your disc. The disc falls to the lowest available slot in that column.

The center column (column 4) is statistically the strongest opening move. It gives you access to the most potential winning lines and limits your opponent's options. If the center is taken, aim for columns adjacent to center. Avoid playing on the edges early unless necessary. Expert players often focus on building "double threats"—positions where you have two ways to complete four in a row.

Easy: The AI makes mostly random moves with basic blocking. Great for beginners.
Medium: Uses heuristic evaluation—prioritizes center control, blocks obvious threats, and looks 1-2 moves ahead.
Hard: Employs a minimax algorithm with alpha-beta pruning, searching up to 5-6 moves ahead. It evaluates millions of positions to find optimal moves. Quite challenging!

Yes! If all 42 slots are filled without either player connecting four, the game ends in a draw. Ties are relatively rare in casual play because Connect Four is a "solved" game—with perfect play, the first player can always force a win. However, against a strong defense or in beginner games, draws do happen.

Traditionally, the red player (Player 1) goes first. In our PvP mode, Player 1 (Red) always starts. In AI mode, you (Red) go first against the AI (Yellow). First-move advantage is real—mathematically, the first player can force a win with perfect play, which is why competitive Connect Four sometimes uses a "pie rule" or alternating starts.

Yes! Connect Four was mathematically solved in 1988 by James D. Allen and independently by Victor Allis. The first player can force a win with perfect play by starting in the center column. Our Hard AI uses this knowledge—if you give it the first move, it will start in the center. Try to beat it! The solution involves complex game tree analysis with over 4.5 trillion possible positions.

1. Ignoring the center: The center column is the most valuable real estate on the board.
2. Playing too defensively: Only blocking without building your own threats leads to eventual defeat.
3. Not scanning diagonals: Many beginners miss diagonal threats until it's too late.
4. Stacking too high in one column: This limits your future options and can backfire.
5. Overlooking "odd-row" threats: On odd-numbered rows, certain patterns create unstoppable double threats.

Our current PvP mode supports local two-player gameplay on the same device—perfect for passing the phone or playing side-by-side on a tablet. For true online multiplayer with friends, you'd need a backend server. We recommend using screen sharing or playing locally for the best experience. The AI mode offers a great solo challenge anytime!