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In a 1993 interview with the game's director/designer Rieko Kodama published in several shorter pre-release magazines, she was asked if there'll ever be 3D dungeons again in Phantasy Star? She responded:

"Whenever you release new hardware or equipment, users are going to have high expectations for it. For example, with the Sega Master System, the 3D dungeons in Phantasy Star probably grabbed a lot of attention for that reason. I know we’ve had a lot of requests to add the 3D dungeons back in for the Megadrive Phantasy Star games. However, players won’t be satisfied with SMS-era technology for the 3D dungeons in a Megadrive game, and it doesn’t make sense with our design plans either: everything has to be rotatable, floors, ceilings, etc, and that would take up far too much memory."

"Anyway, developments always have to be try push beyond what players expect. For that reason, we abandoned the idea of 3D for PSIV. The first games that were developed for the Megadrive, like Alex Kidd and Altered Beast, graphically speaking it’s kind of surprising now to look back and see how many flaws they have, but no one was used to developing for the Megadrive then. To be honest, it wasn’t until Phantasy Star II that we really became competent with the Megadrive’s capabilities—which is why, in that sense, that game had a very high level of technical polish."
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According to a 1993 World of Phantasy Star book interview with Miki Morimoto, she stated that the meaning of the game's title was like “a planet/star of fantasy” and that Yuji Naka was the one who originally named the game Phantasy Star. He started with just the word "Fantasy", and played around with it until he figured out what to name the game. He was also influenced by a song called "Nagisa no Fantasy" (Beachside Fantasy) by his favorite singer, an idol named Noriko Sakai.
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In Phantasy Star Online Rag Rappies are most likely named after the planet Ragol, Al Rappies are most likely named after the Algol system and the Nab Rappies in Phantasy Star Online 2 are most likely named after the planet Naberius.

Though they appear on Ragol, Al Rappies are the non-seasonal rare version of rag rappies in PSO, while in Phantasy Star Universe and PSO2 the non-seasonal rare rappy variant is simply called "Rappy" and appear on every planet, suggesting that Al Rappies are rare because they somehow traveled from the Algol system from the classic Phantasy Star games, though they are still considered to be native enemies, while the rare rappies in PSO2 are part of the "another" enemy group.
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The Naula Cake shop, run by a trio simply known as the "cake sisters" or "Naula sisters", who claim to not actually be bakers, is often a hard to find vendor. It is usually found in a cave or cave-like area, that appears in several Phantasy Star titles, and is inspired by the oddly located baker in the Naula Caves of planet Palma in the very first Phantasy Star game and it's enhanced remake, Phantasy Star Generations 1. The cake sisters who run the Cake Shop in later titles are also sometimes host to a Pizza Shack. It is most likely not the same three sisters every time however.
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Attachment The Phantasy Star MMOs contain many references to other ##Sonic Team## titles, including weapons such as the "Sonic Knuckles", which are actually Knuckles' gloves, armor auras, Chu-Chu Rocket themed Go Go Balls, several mag evolutions, cameos from sonic characters, background music for lobbies, player rooms and certain quests, and sonic anniversary lobbies.


A more subtle reference can be found in the christmas lobby music in Phantasy Star Universe and Phantasy Star Online 2. They contain what sounds like an instrumental re-arrangement of the credits theme of Sega Saturn version of Sonic 3D Blast, "You're my hero" as the christmas online lobby background music. Phantasy Star Online however, instead had an instrumental arrangement of "Jingle Bells".
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The name Algol (The Star System from the classic games) is a japanese anagram of Ragol (the main planet of Phantasy Star Online) and ORCAL (The Arks fleet in Phantasy Star Online 2).

The name of the star system in Phantasy Star Universe, Ghurral most likely shares a name origin with Algol, which is named after the binary stars of the same name, whose name was derived from "Ra's Al Ghul" (رأس الغول).
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Similar to the Chocobo in Final Fantasy, the token mascot character of the Phantasy Star franchise, the Rappy, did not appear until Phantasy Star III: Generations of Doom, however, it was known as the Chirper in the US release and had several variants, including the Squaker, Warbler, and their robot forms Chirpbot, Squakbot, and Warblbot.