Introduction Symbio is a game where each player's groups of cells, or pieces, attempt to surround each other. It was inspired by the immune system's ability to surround pathogens. Two players, Black and White, take turns to either place or move one of their pieces adjacent to another of their pieces, on an 8x8 board. 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. Definitions In these rules, "adjacent" always means "orthogonally adjacent". A body is an adjacent set of pieces of the same colour. A foreign body is an opponent's body. A body has freedom if at least one of its pieces is adjacent to an empty square. Play At the start of the game, Black pieces are placed on b6, b7, c7, f2, g2 and g3, and White pieces are placed on b3, b2, c2, f7, g7 and g6. Black plays first, then turns alternate. On their turn, a player must first move one of their bodies and then add a piece to the board adjacent to one of their bodies. The movement of a body involves taking a piece from the body and moving it to a different square adjacent to the body (including squares adjacent to the piece itself). A body cannot move unless it has freedom. A body's move may land on a foreign body piece, thus removing it from the board, if that foreign body has no freedom. A player wins if their opponent cannot add a piece next turn. This will occur if the opponent has either no remaining pieces on the board or no remaining bodies with freedom. Notes The movement rules result in a pseudopod-like movement which may split a body into two smaller bodies (meiosis). Conversely, movement may result in two or more bodies coalescing. Players should strive to surround foreign bodies and eat them away while giving their own bodies as much freedom as possible. Keeping a foreign body surrounded ties up pieces. Cycles are possible.