Osomatsu-kun Hachamecha Gekijou

Osomatsu-kun Hachamecha Gekijou (おそ松くん はちゃめちゃ劇場) is a Sega Mega Drive action game developed by Sega R&D 2 and published by Sega. Based on the Japanese media franchise Osomatsu-kun, it was released exclusively in Japan in December 1988, and alongside arcade ports like Super Thunder Blade and Altered Beast was the first original game developed for Sega's new 16-bit platform. Notable for its overwhelmingly poor critical reception, the game gained a cult reputation as one of the worst games on the system.

As Osomatsu-kun predates the development of the TradeMark Security System, it will only function properly with Japanese or Asian consoles, or model 1 systems which lack TMSS - but this can be bypassed with use of a Game Genie.