I never implemented anything in Zillions, but I had the impression that it is orders of magnitude more difficult than configuring Nebiyu or Sjaak II for games these can handle. You have basically to write your own move generator for the involved pieces in some cumbersome, LISP-like programming language, rather than just specify a FEN and a list of participating pieces as in Sjaak or Nebiyu.
I never implemented anything in Zillions, but I had the impression that it is orders of magnitude more difficult than configuring Nebiyu or Sjaak II for games these can handle. You have basically to write your own move generator for the involved pieces in some cumbersome, LISP-like programming language, rather than just specify a FEN and a list of participating pieces as in Sjaak or Nebiyu.