  In a biased weak $(a,b)$ polyform achievement game, the maker and the breaker
alternately mark $a,b$ previously unmarked cells on an infinite board,
respectively. The maker's goal is to mark a set of cells congruent to a
polyform. The breaker tries to prevent the maker from achieving this goal. A
winning maker strategy for the $(a,b)$ game can be built from winning
strategies for games involving fewer marks for the maker and the breaker. A new
type of breaker strategy called the priority strategy is introduced. The
winners are determined for all $(a,b)$ pairs for polyiamonds and polyominoes up
to size four.
