Enso

From BoardGameGeek:

Enso is a game inspired by the "Enso"(円相) motif depicted in calligraphy or painting within Zen culture. Unlike most games, the possible moves for a piece depend on its adjacent state in this game: a piece adjacent to an enemy must make a capture; a piece adjacent only to allies can move to an enemy's adjacent space or an unoccupied space without making a capture; and a piece with no adjacent pieces cannot move. The objective is to surround one of your pieces with "empty" - that is, to place it in a position where all eight directions surround vacant spaces.