Launched in South Korea back in 2002, developer AniPark (now part of Netmarble) has officially shutdown Project A3 after a total of 12 years in operations (there was a closure midway). This was actually announced back in Dec 2014, the same year the game was brought back as “A3 Returns” 5 years after the first closure. AniPark revealed there are no more updates, hence the decision.
Once known throughout South Korea and China for its “Adult 18” marketing, Project A3 had a cult following and players were especially attracted to the main character, Princess Radiant. The London Symphony Orchestra was even hired to perform the OST! Developer AniPark has since moved on to develop several successful sports games, and it seems the previously teased Project A4 is no more.