Connect Four Board
Connect Four is an alternating gravity game: a disc always lands in the lowest free cell of its column. The first red or yellow player to connect at least four of their discs in a horizontal, vertical or diagonal straight line wins. A full board with no such line is a draw. Choose a 6×5, standard 7×6, 8×7 or 9×8 board and play together or against a small, deterministic browser-local opponent.
Key features
- Gravity placement into the lowest open row and rejection of full columns
- Exact vertical, horizontal and both diagonal four-in-a-row checks with highlighted winning discs
- Four size presets, alternating turns, win/draw state and move record
- Two-person play or deterministic local Yellow opponent that wins or blocks immediate threats before preferring center
- Column-button keyboard arrows, touch controls, undo and reset
How to use
- Choose a board size and a two-person or local-computer mode; Red begins.
- Select an open column using touch or keyboard to drop a disc into its lowest empty row.
- Alternate turns and connect four vertically, horizontally or diagonally; the board highlights a winning line.
- When the board fills without a line, record a draw; use Undo or New game to review or restart.
Use cases
- Practice planning around gravity rather than placing a disc in any arbitrary cell
- See how vertical, horizontal and both diagonal wins are detected
- Play a predictable local opponent or take turns on one shared device
Frequently asked questions
Can I choose a row?
No. You choose only a column. The disc falls to the lowest available cell; a full column cannot accept another disc.
What counts as a win?
At least four same-color discs in one uninterrupted horizontal, vertical or diagonal line. All connected winning discs through the final move are highlighted.
When is it a draw?
If every cell is occupied and the final move created no four-in-a-row, the game is a draw.
How does the local opponent choose?
It takes an immediate winning column, otherwise blocks an immediate opponent win, otherwise chooses the most central open column. It does not search future turns or claim strong play.
What does Undo do against the computer?
It returns to the start of the previous human turn, undoing the computer's response too if one occurred.
Privacy
Boards, move logs and computer choices stay in the current browser tab. No game state is sent to an API or saved across reloads.
Comments & questions