Well:
"When the players got stronger they found that playing with "completely free" rules was in great favour of Black (the beginner of the game). It is also proved that there is a sure win for Black when playing with "completely free" rules."
(from http://www.renju.nu/r1rulhis.htm)
The rule "no-more-then-five for black" is one of "black" restrictions in renju.
(убрать) У Вас настроение для быстрой игры, которая гарантированно закончится за 2 часа? Создайте новую игру, выберите Время для игры и установите Время 0 дней/1 час, Бонус 0 дней/0 часов и Лимит 0 дней/1 час. (TeamBundy) (Показывать все подсказки)