Game Boy

Ninja Gaiden: Shadow

Trivia

And in addition to Zohvi's entry, this also explains why "Shadow Warriors" doesn't have an original soundtrack, but rather are made of - excellently - converted songs from the NES series.

This game was originally a ninja-themed sidescroller by the name of Shadow of the Ninja, released as such only in Japan. Tecmo acquired the rights to it and after some cosmetic changes released it internationally as a prequel to it's long-running Ninja Gaiden series (that takes place 3 years PRIOR to the original game) under the name of "Ninja Gaiden: Shadow". I have no idea however, why the (later) European release ditched the Ninja Gaiden brand name and adopted the "Shadow Warriors" title.