shoot-'em-up
/ˈʃuːtəmˌʌp/noun
1- informal a fast-moving story or film, of which gunfire is a dominant feature〈非正式〉描写枪战的故事（或影片）。
1.1
- a simple, strategyless computer game in which the sole objective is to kill as many enemies as possible to achieve a high score（电脑中的）杀敌游戏。