Each number moves like a chess knight, i.e. to the opposite corner of an
mxn rectangle where mn is no greater than the value
of the piece. For
example, the number 6 moves like a standard chess knight
(m = 2 or 3, n = 3 or 2)
or like a pawn (m = 1, n = 2 or 3), or in several other
possible ways.
An exact move is one for which mn equals the value of the
piece; capturing is only allowed on exact moves. If a move is inexact,
then the piece is reduced in value to mn, and the difference
between that and the original value is left behind on the original
square. If the target square is occupied by another piece of the same
player, the values are added.
The goal is to simultaneously occupy the opponent's home squares (where
her first pieces
are originally placed).
Note that you may need to install extra fonts for this to display
properly. On linux I've found that symbola, dejavu, and droid do the
trick.