The multiplayer online game, which went live in 2006, was still in operation in Japan until Sonic Team pulled the plug in the Asian territory this week.
Sonic Team brought an end to the PC and PlayStation 2 versions of Phantasy Star Universe in 2010, but the Xbox 360 edition remained live in multiple territories until earlier this year, when Japan became the only country with active servers.
Phantasy Star Universe was Sega's follow-up to Dreamcast classic Phantasy Star Online, the first multiplayer online game ever to be released for a home console.
Many of the series' hallmarks have been carried over to modern entries in the franchise, such as the PlayStation Portable's Phantasy Star Portable series.
Phantasy Star Universe players have taken to the game's official forums to share screenshots and memories of its time online.
Watch a trailer for Phantasy Star Universe below: