Description taken from Arcade version of this game

Space Harrier is a fast-paced shooter notable for its colorful, pseudo-3D visuals. You control a surprisingly agile human in a mission to save a futuristic world from a hostile threat. Viewed from a third-person perspective positioned behind the protagonist, Space Harrier involves blasting an assortment of unusual creatures moving steadily toward the screen with the hero's two-handed laser cannon. The game's 18 stages take place on different regions of the planet, as you travel across grass, desert, and other terrain while avoiding (or shooting) obstacles such as trees, pillars, and rocks. Quickly dodge oncoming projectiles by moving left and right, while targeting anything that moves, including end-of-stage boss creatures. The arcade version was released in three varieties: an upright cabinet with a 20" monitor, an upright cabinet with a short chair attached to the base, and a deluxe sit-down cabinet with a motorized cockpit that moved in unison with the flight-stick controller. ~ Scott Alan Marriott, All Game Guide