Symbio was inspired by the immune system's ability to surround pathogens, and so the game creates a system where each player's groups of cells, or pieces, attempt to surround each other.Players either place or move one of their pieces adjacent to another of their pieces, on an 8x8 board, every turn. In order to make a move, the players' formations of pieces must have an open space adjacent to them. The game ends when one player can no longer make a move. - BoardGameGeek