is a 1987 role-playing video game (RPG) developed and published by Sega for the Master System. One of the earliest Japanese RPGs for consoles, it tells the story of Alis on her journey to defeat the evil ruler of her star system, King Lassic, after her brother dies at his hands. She traverses between planets, gathering a party of fighters and collecting the items she needs to avenge her brother's death and return peace to the star system. The gameplay features traditional Japanese RPG elements including random encounters and experience points. All the characters have predefined personalities and abilities, a unique element compared to the customizable characters of other RPGs of the era.

Sega launched the development of Phantasy Star so their Master System could compete with the burgeoning popularity of console RPGs, particularly Dragon Quest (1986) on the Famicom. Designer Kotaro Hayashida and programmer Yuji Naka formed a team, staffed by a large number of women for the time, including graphic designer Rieko Kodama. The team wanted Phantasy Star to be a unique RPG experience, so they added elements like 3D dungeon crawling, a female protagonist, and ample animation. The game's setting was a fusion between medieval fantasy and science fiction, an idea inspired by Star Wars. The team had to use several techniques to fit all their content on a four megabit cartridge, a large game size for the time.

The game was released for the Master System two days after Final Fantasy arrived for the competing Famicom. It was praised for its grand sense of adventure due to its advanced visual effects and deep gameplay. The battery backup system drew praise but also contributed to the game's notably high retail price which made it difficult for some critics to recommend. The game was re-released on several platforms in the following years, including a series of Phantasy Star compilations. In 2003, a remake titled was released for the PlayStation 2.

Phantasy Star is considered a landmark RPG for its use of predetermined characters and a science fantasy setting. Sega launched a series of sequels, some of which were developed by staff who worked on the original. Kodama directed Phantasy Star IV: The End of the Millennium (1993) and Naka produced Phantasy Star Online (2000).

Gameplay

thumb|left|Alis battles two "Owl Bear" enemies near the start of the game, although only one is rendered onscreen.

Phantasy Star is a traditional Japanese role-playing game. Chunsoft and Enix's Dragon Quest series was proving to be very popular on the Famicom, inspiring other developers to design similar games. They believed they could not rely on third-party support because Sega's hardware market share was only one-tenth that of Nintendo's. They had previously been recognized for their work within Sega — Hayashida for Alex Kidd in Miracle World (1986), Hayashida was lead designer and Naka was lead programmer. Hayashida believes he had the largest role in shaping the game as lead designer and scenario writer, although Ohshima recalls Naka leading the project. One approach was with the setting. The team was strongly influenced by Star Wars and how it combined Western culture with Japanese touches, such as how clothing resembled judo uniforms, and lightsabers were used like samurai swords. Kodama went through about a dozen designs until she achieved a strong but feminine character, one with whom female gamers could empathize. In spite of the chip's capacity, the team made many compromises to save space. The game was compatible with the Master System FM synthesis expansion unit which housed a Yamaha YM2413 chip that added nine more mono channels to the console's programmable sound generator (PSG), the Texas Instruments SN76489. The expansion gave the soundtrack a wider range and heavier bass. The unit was not released outside Japan. This version was identical to the Master System version but lacked FM sound enhancements. In 2018, a port developed by M2 was released through the Sega Ages label for the Nintendo Switch. Naka's tricky programming efficiencies to save memory in the original proved difficult for the programmers handling the port. The two remakes were released on the PlayStation Network in Japan as PS2 Classics in 2014.

|rev1 = Console XS

|rev1Score = 95%

|rev2 = S: The Sega Magazine

|rev2Score = 94%

|rev4 = Sega Pro

|rev4Score = 96% Electronic Game Player felt the game was leading the industry into a new era of console RPGs. Sega Pro called it the best RPG on the Master System, and Zzap! called it a must-have for RPG fans. Boys' Life wrote that along with The Legend of Zelda series, "Phantasy Star may represent the future of home video games" by combining "the graphic quality of arcade games with the complexity of computer games". Computer and Video Games felt it was a massive and sprawling game, and were left impressed visually and aurally. Many reviewers enjoyed the dungeons, thinking the lighting and perspective effects made for a realistic presentation.

The game was difficult to recommend for some because of its high price.

On its re-release for the Sega Mega Drive in 1994, a number of the four reviewers in Famitsu found the game

's graphics dated with one reviewer saying the game was very unbalanced from the beginning as it starts out very difficult. One reviewer commented that the game had been re-released too many times and it should have been remade or have some extras to justify a re-release. GameSpot and G-Force wrote that the graphics pushed the Master System to its limits, and helped set the game apart in its time. Some critics commented that the game felt too standard compared to modern RPGs. Some also felt it was more difficult and dull than modern offerings due to heavier grinding. The Game Boy Advance version was commended for being a good emulation but criticized for poor sound and missed opportunities for enhancements. It is credited with helping to define the genre and introduce the West to console RPGs. Nintendo Life called it a killer app which "not only tested the hardware but also the boundaries and expectations of the genre". The following year it was ranked the 62nd best console video game of all time by Electronic Gaming Monthly, the only appearance of a Master System game on the list. In 2001, Game Informer included it on its own list of greatest video games at #94. The staff praised it for its innovation and graphical superiority (specifically to Dragon Warrior).

The game introduced many elements that later became staples of the RPG genre. Its fusion of science fiction with medieval fantasy contrasted with the traditional fantasy seen in other RPGs of its era. The graphics are considered ahead of their time, particularly the 3D dungeons and monster animations. Both programmer Yuji Naka and artist Rieko Kodama worked on the sequel Phantasy Star II (1989), She later served as producer on Skies of Arcadia (2000), a critically acclaimed RPG for the Dreamcast. Character designer Naoto Ohshima went on to create the character Sonic the Hedgehog and collaborated with Naka on several games including the Sonic the Hedgehog series, Nights into Dreams (1996), and Burning Rangers (1998); Sonic Team would later take over the series.