Zanac (USA) is the American release of the side-scrolling shooter originally released on arcade platforms. This version might include changes to accommodate the American market, such as altered graphics or revised difficulty levels.  The core gameplay is likely similar to the Japanese and arcade versions, centering on spaceship combat against hordes of enemies.  A different publisher or distributor is likely responsible for the US version.

Zanac (USA)

Yuushi no Monshou - Deep Dungeon (Japan)