itch.io

First-Person Shooter refers to a genre where the camera is at the same place as your eyes: you see (on screen) the scenes just like you'd experience it.

Science-fiction. Commonly including things like aliens, advanced technology, and settings of outer space or distant planets. 

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.