Yu-Gi-Oh! trivia from PsychoSpaceCow

[Psychospacecow]

Ever heard of a gem called Yu-Gi-Oh! Forbidden Memories? It was the only Yu-Gi-Oh! game for the playstation one, and it plays completely differently from the main game, going by different rules involving celestial bodies, different spell/trap card effects (for example,in the card game, dark hole destroys all monsters on the field and sends them to the graveyard. In this game, an actual black hole opens up and takes away all cards, not just monsters)(and monsters outright don't have effects), using a different system of fusion, and completely ignoring the star rules all together. Rather fun, albeit difficult game honestly, but that's not why I'm here.

This game, which was released on December 9th 1999 for Japan actually created some characters that would be used in the anime later on, actually creating an entire arc of the series based around the main cast's ancient egyptian incarnations.

http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_F...n_Memories
http://yugioh.wikia.com/wiki/Guardian_Star

Shimon Muran (Simon in the game) first appeared in this game as the pharoah's tutor. He would go on to make his first appearance in episode 201 "Memoirs of the Pharoah which aired April 21st 2004 in Japan.

http://yugioh.wikia.com/wiki/Shimon_Muran
http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_-_Episode_201

Priest Seto (the incarnation of Kaiba) and Pharaoh Atem (Yami/Dark Yugi, you play as him) appeared in this game originally. Their first appearance was on a museum wall in episode 52 which debuted April 24th 2001 in Japan.
Ishizu Ishtar first appeared in this game and episode as well.

http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_-_Episode_052
http://yugioh.wikia.com/wiki/Priest_Seto
http://yugioh.wikia.com/wiki/Pharaoh_Atem
http://yugioh.wikia.com/wiki/Ishizu_Ishtar

Maximillion Pegasus appeared on the first episode of the second series of Yu-Gi-Oh! and he still appeared first in this game. (there was an original series which didn't focus on the card game. It has the card game, but it was more about Yami Yugi killing generally bad people in games, literally)

http://yugioh.wikia.com/wiki/Maximillion_Pegasus
http://yugioh.wikia.com/wiki/Yu-Gi-Oh!_-_Episode_001

Same with weevil, Rex, Mai, and Bandit Keith
http://yugioh.wikia.com/wiki/Weevil_Underwood (episode 2)
http://yugioh.wikia.com/wiki/Rex_Raptor (episode 2)
http://yugioh.wikia.com/wiki/Mai_Valentine (episode 3)
http://yugioh.wikia.com/wiki/Keith_Howard (episode 16)

This is likely because Yu-Gi-Oh! as a brand was going through a transitionary stage, from Bandai to Konami and as a result, nothing would really have been set in stone.