-Generator variant, called "Matrix" ?
-Peces on first rank never move but generate new pieces. Pawn don't generate.
-A generator captured and replaced by a similar piece does not generate.
-King does not generate. No castling. En passant possible?
-Goal is still checkmate.
+NEW VARIANTS:
+http://history.chess.free.fr/rollerball.htm
+ https://www.chessvariants.com/40.dir/rollerball/index.html