Larry Smith wrote on Fri, Jun 19, 2009 05:35 PM UTC:
Those planar pieces which are not restricted by occupancy of their attack plane might actually be classified as 'hook-movers'.
The restriction of planar pieces might seem a little draconian, but only during the early portion of the game. As the field clears, these pieces begin to rise exponentially in threat.
A further restriction was developed because of the dynamics of the diagonal(and triagonal) planar piece. This was that all the cells within the planar move must exist on the field. Though developers and players are not strictly bond by this rule.
For a nice(or so I think) 2D game which demonstrates planar moves, try LiQi. It utilizes the same equipment as the Mad Queen(but it does not restrict the diagonal planar piece). There's also a Zillions implementation.