Games in the genre are most commonly called "comical action games" (CAGs) in Japan.[17][18] The original arcade Mario Bros. is generally recognized as the originator of this genre, though Bubble Bobble is also highly influential.[citation needed] These games are characterized by single screen, non-scrolling levels and often contain cooperative two-player action. A level is cleared when all enemies on the screen have been defeated, and vanquished foes usually drop score bonuses in the form of fruit or other items. CAGs are almost exclusively developed in Japan and are either arcade games, or sequels to arcade games, though they are also a common genre among amateur doujinshi games.