The full version of Moons can be acquired from Regnow (www.regnow.com).

Moons can be best described as "circular Reversi". Adding circles to
reversi enables players to use a unique move which cannot be done in
ordinary Reversi.

Because Reversi is linear, it is necessary to use two pieces surround
your opponent's pieces. But, because Moons is circular, this can be
done using only one piece.