Spline+ is a simple N-in-a-row game that exploits the pyramidal stacking to guarantee a winner.

The board starts empty. Two players, White and Black, takes turns either:

  • placing a ball of their colour either on an empty board hole or to stack on any 2x2 platform.
  • moving a ball of their color to another suitable location. A ball can move only if it has 0 or 1 other ball resting on it.

    • Aim: A player wins by making a full line, orthogonally or diagonally, on any level. That is, lines on the 4x4 (board) level must be of length 4, lines on the 3x3 level must be of length 3, and lines on the 2x2 level must be of length 2.

    The following diagrams show completed games won by White with 3-in-a-row (left) and Black with 2-in-a-row (right).