Atoll is a two player connection game played on a hexagonally tessellated board. The board is surrounded by eight "islands" of stones, alternating between black islands and white islands going around the board. Black must connect two black islands on opposite sides of the board with a contiguous chain of black stones. The islands themselves can be part of the chain. So for example, Black could form one bridge between his North and West islands and a second bridge between his West and South islands to win. Likewise for White and the white islands.
Like Hex, a completely filled-in board must result in a winning connection for exactly one of the two players.
Atoll could be characterised as a generalisation of Hex where the number of islands is eight rather than four. A generalized Atoll can be played with any multiple of four islands.