There are two kinds of pieces in Tafl: the King and Soldier, and they move in the same way. They move any number of squares left, right, up, or down just like a rook in chess. Only the Defenders have a King piece.
Tafl games have assymetrical goals. Unlike chess where both sides have the same objective: to checkmate the opposing king, in Tafl the Defenders are tasked with helping the King piece escape to the edge or corner (rules vary on this) and the job of the attackers is to capture the Defender's King piece before it can escape.
Capturing in Tafl is different from other games like chess where a capture is performed by occupying an enemy piece's square or checkers/draughts where a capture is performed by jumping over an enemy piece. In Tafl captures are done via "custodian capture". Custodian capture requires two pieces. One piece must be adjacent to an enemy piece then another piece moves such that it is also adjacent to the enemy and it is in a straight line from the friendly piece that is already adjacent to the enemy. The enemy piece between is then removed from the game board. A piece that freely moves between two enemy pieces is not captured. Some rules variations require that the King be captured by four surrounding pieces instead of just two.
Special squares (the center square and four corner squares) may only be entered by the King. However, any piece may move over a special square. In some rules variations the King may not re-enter the center square after leaving it. These special squares, when unoccupied may be used as a friednly piece for the sake of performing a capture for either side.
The attackers move first.
Tafl can be played on a variety of board sizes, the ratio of Attackers to Defenders is always 2:1 plus the Defender's King.