Phantasy Star IV is an archetypal role-playing video game, featuring the staples of exploration, NPC interaction, and turn-based combat.

Phantasy Star IV has a number of features new to the series, including combination techniques, manga-style panel illustrations that accompany the narrative, and an expanded script.

To make matters worse, there has been a marked increase in the numbers of the "biomonsters", a catch-all term for the strange and violent aberrations of Motavia's flora and fauna.

Hired by Piata Academy on Motavia, hunters Alys Brangwin and her young apprentice Chaz Ashley begin their investigation into the relationship between the biomonster problem and the planet's ecological crisis.

Joined by others along the way, they connect the world's troubles to a cult leader called Zio, "The Black Magician", whose aims appear to be total annihilation of not only Motavia but of the whole Algol solar system.

With the seal now severely weakened by the planet Parma’s destruction during the Great Collapse, Chaz and his party enter the Profound Darkness’s dimension and eliminate it before it is able to break completely free and destroy the galaxy.

With the evil banished for good and the party going their separate ways, Rika — a numan girl in the group — chooses to stay behind with Chaz as they bid everyone farewell, remembering the sacrifice of those who have defended Algo through the ages and awaiting the next one to come.

Phantasy Star IV: End of the Millennium received generally positive reviews upon release, with critics praising the gameplay but with mixed reactions to the story and graphics.

[19] The four reviewers of Electronic Gaming Monthly commented that the magic/technique system, equipment and general gameplay are all highly involving and enjoyable, but that the graphics are mediocre, the music is irritating, and the story is too slow-paced.

"[8] The three reviewers of GameFan rated it 90, 97, and 92, stating the "graphics are beautiful, the music is powerful, and the non-stop original ideas make this cartridge an absolute must-own for the RPG enthusiast" while criticizing the translation.

In RPGamer, Sephirstein praised the title as one of the greatest RPGs he had ever played, with "magnificent graphics, sensational soundtrack, gripping story and incredible battle system".

[20] IGN called it one of the definitive 16-bit role-playing games, stating the "storyline and characters are deep and engaging", the "attractive anime-style cutscenes steal the show visually", and the gameplay is both "classic and unique at the same time".