Your turn — connect top to bottom
The classic connection game, invented independently by Piet Hein and John Nash. The board is a rhombus of hexagons. You play red and try to build an unbroken chain of your stones joining the top edge to the bottom; the AI plays blue and races to join left to right. Whoever links their two sides first wins — and a beautiful theorem proves the board can never end in a draw, so every game has a winner. Easy to pick up, fiendishly deep, and over in a couple of sharp minutes.
The board is a 7×7 grid of hexagons tilted into a rhombus. Two opposite edges are tinted red (top and bottom) and the other two are tinted blue (left and right). You are red; the AI is blue. Red moves first.
On your turn, tap any empty hexagon to drop a red stone there. The AI then answers with a blue stone. There is no capturing and nothing ever moves — every stone you place stays put for the rest of the game.
Each hexagon touches six neighbours: the two beside it, and two above and two below (offset, because the rows are staggered). Your stones count as connected when they touch along these neighbours, forming a chain that can wind and branch across the board.
Your goal is a single unbroken chain of red stones that reaches from the top edge all the way to the bottom edge. The AI is trying to do the same thing sideways, from the left edge to the right. Because any chain of yours that crosses the board top-to-bottom must block every possible left-to-right blue chain, the two goals cannot both succeed — exactly one of you connects, and that player wins. Draws are impossible.
Win to extend your streak. Each win raises the number of positions the AI evaluates, so it plays sharper the further you climb.
Build through the middle, not the edge. A chain that climbs the centre of the board has room to dodge around blocks on either side, while one hugging a wall is easily sealed off. Start by claiming central hexes and grow outward from there.
Learn the bridge. Two of your stones placed a knight's-step apart — with two empty hexes between them that each touch both stones — are 'bridged': if the AI plugs one gap you simply take the other, so the link cannot be cut. Bridges let you advance twice as fast as solid chains while staying safe.
Every move is attack and defence at once. Because blocking the AI's left-right path and extending your own top-bottom path are the same battle, the strongest stones do both: look for a hex that lengthens your chain while sitting squarely in the AI's way.
Watch the opponent's shortest route. If the AI is one or two stones from joining its sides, stop reaching for your own win and place the stone that breaks its connection — a move that defends a loss is worth more than one that chases a win you won't reach in time.