Object: Checkmate the opponent's King.
 
If possible, you have a similar second move (a 'TWIN MOVE') with another piece of the same type.
A Twin Move is a move into the same direction and going the same distance. For example, after a2-a4 you may play h2-h4 as the second partial move. You cannot play h2-h3 however. Similarly, your second move may be Rook a1-a2 plus Rook h1-h2.
 
In the default variant the Twin Move is always forced. Only if this second move is not possible you may 'pass' a move by clicking on an empty square.
 
In the second variant the Twin Move is optional. You can always pass the Twin Move by clicking an empty square.
 
 
For more freeware as well as real puzzles and games see my home page http://karl.kiwi.gen.nz.