It was later ported to a wide variety of consoles, including the Sega Master System. The player controls a sentient robot/spaceship named Opa-Opa who fights an enemy invasion in the titular group of planets.
The game contains a number of features atypical of the traditional scrolling shooter. Its main character, Opa-Opa, is sometimes referred to as Sega's first mascot character ever.
Numerous sequels of the game were made and many have been ported to home consoles over the years.
The game design and main character had many similarities to the earlier TwinBee, and together the games are credited with the creation of the cute 'em up subgenre.
Fantasy Zone and Space Harrier share the same fictional universe.