Complex sentence: The game was originally scheduled to be released as an unrelated game in Japan titled, however that version was canceled and instead Konami localized the game for a North American release as a "Contra" spinoff.
Split into simpler sentences: The game was originally scheduled to be released as an unrelated game in Japan titled. The Japanese version was canceled and instead Konami localized the game for a North American release as a "Contra" spinoff.