Object: Remove all tokens from the board.

Setup:
Click the board to let the system randomize the setup.
The system will drop tokens onto the board positions (which are at the intersections of the lines).
The system will drop a series of formations consisting of four tokens each which are positioned at the corner of an imaginary square, the square's sides being horizontal, vertical or diagonal.
For example, a2-b1-c2-b3 is a permitted square formation.
PLEASE NOTE: This a2-b1-c2-b3 shows that not all square formations have an associated square of lines drawn on the board.

When a new token falls on top of an existing one, the token will show the height of the pile.

Move: You click two corners of a square to eliminate the four pieces which make up the square formation.
For squares which are orthogonally aligned you have to click the lower left and the lower right corner.
For squares which are diagogonally aligned you have to click the left and the bottom corner.

The goal is to have no tokens left on the board.

Variants:
The variants have more and more tokens dropped.
There are also 4 variants using the smaller 9x9 board.