Introduction

Konobi is a drawless connection game for two players: Black and White. It's played on the intersections (points) of a square board, which is initially empty. The top and bottom edges of the board are colored black; the left and right edges are colored white.

Definitions

Two like-colored stones are strongly connected if they are orthogonally adjacent to each other, and weakly connected if they are diagonally adjacent to each other without sharing any strongly connected neighbor. Note that two stones of different colors are never considered to be connected.

A chain is a set of connected stones.

Play

Starting with Black, the players take turns placing stones of their own color on empty points of the board, one stone per turn.

It's illegal to make a weak connection to a certain stone unless it's impossible to make a placement which is both strongly connected to that stone and not weakly connected to another.

It's also illegal to form a crosscut, i.e. a 2x2 pattern of stones consisting of two diagonally adjacent Black stones and two diagonally adjacent White stones.

If a player can't make a move on his turn, he must pass. Passing is otherwise not allowed. There will always be a move available to at least one of the players.

The game is won by the player who completes a chain of his color touching the two opposite board edges of his color. Draws are not possible.

Pie rule

The pie rule is used in order to make the game fair. This means that White will have the option, on his first turn only, to change sides instead of making a regular move.