Shoot-em-up games, or shmups, consist of lone or small groups of players shooting at and being shot at by hordes of colorful enemies. The genre is thought to have peaked in the mid-'90s, but recent games in the indie world may be saying otherwise. Geometry Wars and other twin-stick games kicked off the trend, but newbies Trouble Witches NEO, Outland and just-released Gatling Gears have brought some much needed originality into the modern shmup scene—making it something worth exploring again.