The following article is a brief summary of an interview originally published in Japanese on August 4, 2021 on 4gamer.
Akiko Itō (left) started working on the license during the production of Angelique Special 2 (1996).
Mei Erikawa (right), daughter of the founders of Koei was still in high school during the development of the 1st episode, but she did playtesting on the game since her mother felt that she was the core target.
Koei co-founder Keiko Erikawa had been thinking of making games for women since the 1980s according to her daughter. She submited a proposal that was refused at the time because people thought within Koei (which was then producing mainly strategy games for computer) that the number of female players was too low and that the game would not sell. However, the Famicom was already popular at that time, and Erikawa felt that if half of the world's population were women, then a game should be made for them. So she insisted on making a game by women for women. It took her 10 years to put together a team of female developers.
The characters in Angelique were inspired by various manga and anime series and incorporated elements that Akiko Itō said appeal to women, namely Greek mythology and astrology.
The game went unnoticed at the time of its launch, but things began to change when a women's magazine asked to interview its creators and male gamers also began to express interest in the game.
By the end of 1995, with the release of the PC-FX version, the game now had spoken dialogues, an element that would greatly contribute to the game's sales. The Super Famicom version even benefited in 1996 from a slightly reworked reissue bundled with a CD and an infra-red adapter (Voicer-Kun, a device that the SFC adaptation of the EMIT series was already using in 1995) allowing to play spoken dialogues while playing the game.
Angelique: Voice Fantasy, the reworked version of the original game
The game hasn't sold as much as the big titles in other genres - an otome is considered a success if it sells ~100,000 copies - but it's part of a larger business model that includes drama CDs and music albums on which you can here the voice actors sing as well as live performances with the said voice actors.
The main character of the first episode was 17 years old while the one from the new episode (released in May 2021 on Switch) is 25 years old and has been working as an employee in a company for 3 years. Mei Erikawa explains that Angelique (the series' main character's given name) is basically a projection of herself. The project was launched around the time of the 25th anniversary of the series which is an additional argument to justify the choice of the age of the heroin, even if her age apparently didn't make too much debate internally. However, a balance had to be found to avoid leaving out players who are still in high school and who do not yet have the same perspective and experience as older players who have a full time job.
The game tries to reflect the evolution of Japanese society, in which women no longer have to stop working once they are married or have a child (according to Erikawa), that they can choose between work and family. When Erikawa and Itō were figuring out what the "best ending" of the game was, people told them that they didn't like the idea that falling in love was the best way to go.