Exerion is a vertical-scrolling shooter, where the player's ship would shoot upwards to take out waves of enemies. Though most of the screen was a static black, on the bottom half of the screen the player could see the horizon of whichever planet they were on rushing towards them, including various geographical fixtures whizzing past in a manner similar to parallax scrolling.
The game is an example of an early shoot-em-up: There are no power-ups, just waves of enemies. Players had a limited number of lives and had to start over once they ran out. Enemies, rather than departing the screen upon passing the player's ship, would home in towards them in order to collide with and destroy them: The player had to circle back around and maneuver underneath the enemies in order to shoot them down.
Exerion had four versions: The original 1983 arcade version, its initial MSX home version of the following year, a Sega SG-1000 version and an eventual Famicom version in 1985. The Famicom version would also be rereleased on the Wii Shop's Virtual Console decades later. The arcade version, though the best looking, was also the hardest to play as the ship had a strong sense of inertia and momentum to it, making it sluggish to move and difficult to control. The home versions were better regarded.