Hammerin' Harry, known in its Japanese homeland as Daiku no Gen-san (Gen the Carpenter), began as an arcade game by Irem that soon spun off into several different incarnations. The real star of the game is the hero's gigantic hammer, which, in addition to pounding enemies into submission, also has a number of various uses that differ from game to game.
The series is centered around the titular Harry (or "Genzo Tamura" in the original Japanese), a hammer-wielding carpenter who protects his hometown of Beranme from the corrupt construction companies that mean to tear it down.
This is an English fan-translation of the Japanese Game Boy Color release, letting you enjoy this fantastic action platformer in English on your Game Boy Color.