Keys "s"=save "l"=load "b"=back once
Philip Cohen's modification from 1979. Rooks are 1,0 or 2,0 or 3,0 riders.
Bishops are 1,1 or 2,2 or 3,3 riders.
Knight are 1,2 riders.
Queens are 1,3 or 2,3 riders. Thus all nine kinds of riders are represented.
These are simple illustrations rather than strong opponents.
Bug reports? -- Thank you! Keep them coming!
