The player who has 5 pieces on the board in a row (horizontal, vertical, or diagonal) first wins.
If a piece or group of pieces of the same color is surrounded by the opponent's pieces, they get replaced by the opponent's pieces.
Setup & Appearance
The game is played on a regular full-sized Go board (19x19).
Note that for online play, there is a center 7x7 and 3x3 outline -- this is purely for orientation, and the 7x7 may be used in examples of patterns & tactics.
One player has black pieces, and the other has white pieces. All pieces are round.
Pieces are played inside the squares on the board, as shown.
If playing in person, use the lines of a Go board instead of the squares.
Surrounding
One of the key strategies in Connect Go is to effectively surround the opponent's pieces, so it is important that "surrounding" is well defined.
To surround a singular piece, each square next to the piece must be occupied by the opponent's pieces.
Next to is defined as being on a game square orthogonally adjacent. Diagonally adjacent spaces are not next to.
A group is a set of pieces connected in a continuous chain (orthogonally). If a set of pieces is split or separated, it forms multiple groups.
To surround a group, each piece in the group must be surrounded by pieces that either belong to the opponent or to the group.
* Note: in the second figure, black's group (highlighted yellow) is not surrounded yet, but may be surrounded in one move if black does not surround white's pieces (also highlighted yellow) on the next turn.
Other Rules
Black goes first, then turns alternate.
When a group or piece is surrounded by opponent pieces at any time, they are automatically switched out for the opponent's color pieces. This does not use either players' turn.
5-in-a-row can be made horizontally, vertically, or diagonally.
If the switching colors of a surrounded group causes either player to gain a 5-in-a-row, the player that got the 5-in-a-row wins immediately.
If the board fills up, and neither player has a 5-in-a-row, the victor is the player with more pieces on the board.
