Unicorn Overlord is a tactical role-playing game in which players take on the role of exiled prince Alain as he leads the Liberation Army in a campaign across the fantasy realm of Fevrith.

[1] During exploration, the player guides Alain across an overworld to enter towns, use services such as blacksmiths and merchants to outfit his army, and engage in story or optional battles.

[4] Towns also include side quests which require the player to gather materials and events where Alain can improve his relationship with a character.

With most of the army siding with Valmore, Ilenia has her personal guard Josef smuggle her son Alain as well as the symbol of Cornian royalty, the Ring of the Unicorn, to safety.

Alain has been raised by Josef on the remote island of Palevia alongside the local priestess Scarlett to eventually take leadership of the Liberation Army.

Accepting his role as the leader of the Liberation Army, Alain travels back to Cornia to take charge, but Scarlett is kidnapped by Galerius for an unknown purpose.

Galerius and Baltro then leave to continue their plans while the spirit of an ancient Great Sage advises Alain to travel to Elheim to unlock the Ring of the Unicorn's true power.

Alain leads the Liberation Army to the surrounding nations, ousting the Zenoiran occupiers, restoring the original leadership, securing their allegiances, and recruiting additional allies.

In addition, Alain learns that Galerius's mind control is a special spell called the "rite of channeling" which allows a Zenoiran soul to possess a living body.

Galerius conquered Fevrith, rebuilt Zenoira, and then killed the divine Unicorn in an attempt to steal its power and grant all Zenoirans immortality.

Alain defeats Galerius in battle, leading to three possible endings: The design concept for Unicorn Overlord was created by Takafumi Noma of Vanillaware in 2014, almost exactly ten years prior to release.

Noma had been approached by company founder George Kamitani after production ended on Dragon's Crown (2013) to create a new fantasy-themed video game.

[4] Production moved slowly due to Vanillaware working in parallel on other projects, including ports of earlier titles and 13 Sentinels: Aegis Rim.

[9] Noma commented that the team were able to incorporate almost everything they wanted into the final product, though it went through multiple large-scale redesigns to the point that each felt like its own game.

[4] The gameplay was designed to give a sense of speed, focusing on an overhead perspective, player freedom, and real-time movement and combat.

[8] The team's goal, along with returning to the studio's established fantasy theme, was a "rebirth" of tactical RPGs, paying homage to earlier titles while making it accessible to genre newcomers.

[10] Speaking about the narrative, Noma stated it was only finalized and completed later in the development process, with its basic setting and gameplay being created first.

[8] In reference to the games from which they drew inspiration, the storyline was written to emphasise commonality across a diverse cast through a linear story, and multiple fantasy races were created for the world.

[13][11] Kanada composed and arranged the score together with Yoshimi Kudo, Rikako Watanabe, Richter, Toki Takeda, and Denys Fontanarosa of Artisan Studios.

[17] Unicorn Overlord was first teased with a short film included in the commercial demo disc 13 Sentinels: Aegis Rim Prologue.

He noted that the changes were acceptable provided they were done with the developer's knowledge and consent, citing equivalent experiences during his work on Final Fantasy Tactics.

[26] Reviewers for Japanese gaming magazine Famitsu positively noted the expansive scope of the story and interactions between Alain and other characters.

[31] Kaan Serin of Eurogamer noted the derivative nature of the narrative, but felt character vignettes expanded and fleshed out the setting.

[30] Zalewski lauded the diverse character designs and detailed animation, while positively comparing the overworld to board game maps.

[31] Lindquist praised the design of environments, battle stages, and freedom of movement in combat, but like other reviewers felt the systems were too complex for casual players.