Shooter: Gameplay emphasis is fast action and twitch reflexes; mostly involving shooting things. Also referred to as "shoot-'em-up" games. Examples: Defender, Tyrian, Xevious, etc. Also used when describing traditional 1st-person shooters such as Doom, Quake, Unreal, etc. Part of the Non-Sports Themes category.
You can browse through games in the MobyGames database that are part of this genre via the game browser.