itch.io

Uses two-dimensional "sprites", 2D images created and used on a flat plane, as opposed to the three-dimensional models or environments found in 3D games.

PICO-8 is a fantasy console powered by Lua. Games are distributed as cartridges which double as PNG  images. 

Pixel Art refers to the charming, simplistic, retro/renaissance style of very-low-resolution graphics, such as from the 1977-1995 Atari, GameBoy, & Super Nintendo (SNES) eras.

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.