I talked with the creator and he thinks that it is better to start with a small number of pieces and during time, increase the number of pieces to the final number. Especially the pieces as Magician, Femme Fatale, Joker or Prince are very difficult to play with and (even more?) difficult to program. A joker for example, imitates the last move of the opponent, but it cannot have the special properties of other pieces, like promotion or royalness.
(kaŝi) Se vi volas ludi kontraŭ ludanto de simila nivelo, vi povas difini intervalon de BKR ĉe invito al nova ludo. Tiukaze neniu kun BKR ekster tiu intervalo povos vidi/akcepti ĝin, (Katechka) (Montri ĉiujn konsilojn)