About

Enigma of Sépia, or EOS for short, is a mobile RPG gacha game made by the company “Unicorn Whale Technology Limited” that started gaining popularity in early 2025 for having a large cast of female characters, which are directly modeled after famous male anime characters, leading to it being humorously dubbed “rule 63 the game.”

Origins

The game launched on October 18th of 2024 for Android, but it would stay mostly unknown until the 14th of January of 2025, when a trailer for the game would be uploaded on YouTube, amassing 53 thousand views. The game would launch from iOS and phones on February 14th. ^[1]

Overview

As with most gacha games, Enigma of Sépia has a large cast of characters, and the player has to use in-game currency in order to get the gameplay, which involves very simplistic automatic group combat, which the player has only limited direct influence over.

Online Reactions

First reports and reactions about the game came from ResetEra ^[2], with netizens being very quick to notice and point out that the characters of the game appear to be direct female copies of known anime characters, with many netizens questioning the legality of such a move, leading to various jokes like calling it “Rule 63 the game,” saying the acronym of the game, EOS, stands for “Out Of Service,” which they believe will be the game's eventual fate. Some others humorously praised the game due to how shamelessly and directly it presented its design inspirations despite the clear copyright infringement present.

YouTube content creators also made videos regarding the game again, questioning how such a game was allowed to exist despite the blatant copyright infringement present. The gaming news sites like thegamer, VG247, ScreenRant, and GamesRadar would also cover the game and the discussions regarding it.

Additional References

Gamefaqs ^[1]
Thegamer ^[2]