Paradox is a 2-players game, white and black.
The goal is to make a straight sequence of 4 stones of the player's color.
Each turn, the player has to pick 2 adjacent stones of different colors and either move them in the same orientation, or switch them.
A player may not play the exact opposite move the the last move played.

For switching, click on either of the previously selected stones.
Note that moving is done by clicking the destination of the 2nd stone.