General
Win by passing the ball to a friendly piece on the opponent's starting line.
The objective of Diaballik is to be the first player to pass the ball to one of your own pieces that is located on your opponent's starting line (the row where the opponent began the game). The ball must be actively passed there — simply moving a piece there is not sufficient.
Setup
Each player places all pieces on their own starting line with the ball on the middle piece.
In the standard setup, each player places all of their pieces in a single row on their own starting line (the row of the board closest to them). The ball is given to the middle piece in that row. The two players' starting lines are on opposite ends of the board, and players face each other.
Setup
Variant: each player begins with 2 pieces already on the opponent's starting line.
In the variant setup (fig. 2), before the game begins each player places 2 of their pieces on the opponent's starting line rather than their own. The remaining pieces (and the ball carrier) are placed on the player's own starting line as normal. This variant changes the opening positional dynamics significantly.
Turn structure
Each player performs at least 1 and up to 3 actions per turn, in any order.
On their turn, a player must perform at least 1 action and may perform up to 3 actions total. The available actions are: First Move, Second Move, and Pass. These actions may be taken in any order the active player chooses. The player cannot skip their entire turn — at least one action must be executed.
Movement
Move a non-ball-carrying piece one step orthogonally (first move action).
As one of their up to 3 actions, a player may move one of their pieces (which is not currently carrying the ball) one step to an orthogonally adjacent position (up, down, left, or right). This is designated as the 'first move' action. Diagonal movement is not allowed for piece movement.
Movement
Move a non-ball-carrying piece one step orthogonally (second move action); the same piece may be moved twice.
As one of their up to 3 actions, a player may move one of their pieces (which is not currently carrying the ball) one step to an orthogonally adjacent position (up, down, left, or right). This is designated the 'second move' action. Importantly, the same piece that was moved in the first move action may be moved again in the second move action, allowing a piece to advance two squares in a single turn.
Special
The ball carrier passes the ball in a straight orthogonal or diagonal line to a friendly piece; no distance limit; line must be free of opponent pieces.
As one of their up to 3 actions, the player whose piece is carrying the ball may pass the ball in a straight line — either orthogonally (horizontally or vertically) or diagonally — to another of the player's own pieces. There is no limit on the distance of the pass. However, the entire passing line (every square between the ball carrier and the receiver, exclusive of start and end) must be free of any opponent pieces. Friendly pieces do not block the passing line. After the pass, the receiving piece becomes the new ball carrier.
Restriction
The ball carrier cannot move using a move action.
The piece currently holding the ball is the ball carrier. The ball carrier is completely prohibited from moving to an adjacent square using either the first move or second move actions. Only non-ball-carrying pieces may be moved. The ball carrier can only change position by having the ball passed away from it (thus another piece becomes the carrier), after which it is free to move on a subsequent action.