There are some Chess variants where there are subvariants that are quite similar. For example there is a variant of Amazon Chess where the Amazons can not capture each other unless the enemy Amazon is unprotected. One possible way to implement such small variants based on what Brainking always has is to create a submenu that will come up when creating a new game that allows a player to select what rules will be used for a particular game, kind of like the autopass feature already in use for Backgammon.
Scott/talen314