Hammer Away (Japan, prototype)

Hammer Away is an unreleased Sega System 18 arcade vertical shoot-'em-up game developed by Santos and set to be published by Sega in 1991. The game was featured at Amusement Machine Show 1991 but is not thought to have been seen since. One theory suggests that from a gameplay perspective, Hammer Away failed to keep pace with more recent competitors, most notably Seibu Kaihatsu's 1990 hit, Raiden. A prototype has since been found.