Unknot

Unknot is played on a hexhex board oriented so that there is a horizontal line of adjacent cells between one pair of two opposing corner cells.

Both players share a pool of stones of a single color and take turns placing then onto empty cells.

Placement restrictions.

The center cell is unplayable throughout the game.
Player 1 may not place immediately northwest of a stone.
Player 2 may not place immediately northeast of a stone.

The game is over as soon as one player completes a loop of pieces around at least one empty cell. This player is then the winner. The game cannot end in a draw, so can also be played with the opposite goal: The player who completes a loop loses.

—description from the designer