Connect Four

Drop discs to line up four in a row before the CPU does. Block, bait and outthink the computer.

Connect Four was solved twice in 1988, independently by James Allen and Victor Allis, and the answer is decisive: the first player wins with perfect play by starting in the centre column. Any other opening move loses or draws.

The strategic idea worth carrying into a real game is parity. Threats on odd rows favour the first player and threats on even rows favour the second, because of who is forced to fill the square underneath. Strong players count that from early on, which is why an apparently pointless move in a far column is often about who ends up making the losing placement twenty moves later.