Simple, fast-paced games with colorful graphics and catchy audio, that require few or no explanations, can be played in short bursts, and usually require a lot of skill. Similar in style and spirit with the arcade game cabinets of the 80s and 90s.
Shoot 'Em Up or shmup games are a subset of shooter games where the player continually moves forward while waves of enemies enter the screen. Both shooting and dodging are critical to advancing. See also Bullet Hell.