Four Wins – Four in a Row

Connect Four as you know it — only with an opponent that really thinks. The classic board game, also known as Connect 4 or Four in a Row, as a strategy game for one or two players. No account and no sign-in: just you against the machine, two of you taking turns on the same screen — or over the net against someone else. Behind the machine there is no random number generator but a negamax search with alpha-beta pruning, move ordering from the centre outwards and a transposition table. On the highest level it searches iteratively as deep as it manages in 1.4 seconds — about thirteen plies on an empty board. Beating it takes planning ahead. FOUR DIFFICULTY LEVELS • Easy — searches two plies and blunders on purpose. For in between. • Medium — four plies, the occasional mistake. • Hard — seven plies, no slips. • Unbeatable — searches until the time is up. The level can be changed at any time,…