How to play
Players take turns dropping a disc into one of the seven columns, and it falls to the lowest empty space. The first to line up four of their own discs horizontally, vertically or diagonally wins. If the board fills up first, it is a draw. Click or tap a column to drop, or use ← → and Enter, or the number keys 1–7.
AI levels
Easy makes plenty of mistakes, Normal looks a few moves ahead, and Hard searches about seven moves deep. The first move alternates between you and the AI each game, and your wins, losses and draws are tallied for each mode.
Tips
The middle column is the strongest — it takes part in the most possible lines. Always check whether your opponent is about to make four before you play, and try to build two threats at once so they can only block one.