Hex

Hex was invented independently by Piet Hein and John Nash in the 1940s. Players take turns placing a stone on any empty hexagon. You (red) try to connect the top and bottom edges with an unbroken chain; the computer (blue) tries to connect left and right. Because the hexagons fit together so tightly, one player must always succeed — Hex can never end in a draw.

The computer measures, for every move, how far each player is from completing a connection, and on Hard and Expert it also considers your best reply.

1. Tap any empty hexagon to place a red stone.
2. Connect the top edge to the bottom edge (pink cells) with touching red stones.
3. Block the computer from linking left to right (light blue cells).

• Play in the centre early.
• Use bridges: two stones with two shared empty neighbours can't be cut — if one gap is filled, take the other.
• Block from a distance rather than right in front of the opponent's stones.