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Attachment Milla Jovovich, the actress who plays Alice from the Resident Evil live-action movie franchise, has previously expressed her desire to have her character appear in the game series. She was later disappointed that Capcom never took interest in the idea:

They use... set pieces from the movies in the games but for some reason, they don’t want to put my character, Alice, in the game... It’s a shame because I used to play the game with my little brother years ago and it would be so cool to be in one.
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The famous laser scene from the first Resident Evil movie from 2002 has gotten recreated a total of three times within the games, in Resident Evil 4, Resident Evil 6 and Resident Evil: The Umbrella Chronicles.
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The Red Queen AI, first featured in Resident Evil: The Umbrella Chronicles, actually originates from Paul W.S. Anderson's live action Resident Evil films.
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The title voices for Resident Evil 2, Resident Evil 3: Nemesis and Resident Evil Code: Veronica X for the Gamecube were changed to match the title voices of Resident Evil and Resident Evil Zero, both of which were released on the Gamecube before them.
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According to early concepts of the first game, Jill Valentine is half French, half Japanese. She also has a Japanese cousin who has never been seen outside of some early concept art.
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Leon Kennedy was originally going to be called Grant Bitman.
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Attachment The mysterious company mentioned by Ada Wong in Resident Evil 4 that, at the time, only went by the name "S" was later revealed to be Tricell by the official Resident Evil: Degeneration artbook. The company's name was originally going to be Seashell, thus the "S", but it was changed and the abbreviation got retconned into a codename.
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According to Alyson Court (the voice of Claire Redfield), Claire's Resident Evil 2 design was possibly based off of Neve Campbell, while her Resident Evil Code: Veronica design was based on Liv Tyler.
subdirectory_arrow_right Resident Evil Portable (Game)
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Attachment There were plans to make a Resident Evil game for the PlayStation Portable with the working title of Resident Evil Portable. After its announcement at E3 2009 however, the game was never heard of again and is presumed cancelled or that its development shifted to Nintendo's 3DS and resulted in Resident Evil: Revelations.
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Up until Resident Evil: Revelations 2, Claire Redfield was the only character to retain the same voice actress (Alyson Court) in all the games she has been in, as well as the film, Resident Evil: Degeneration.
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Richard Waugh, the second voice actor for Albert Wesker, was inspired by the Walt Disney villain Shere Khan from "The Jungle Book".

My kids were toddlers at the time and we had been watching a lot of Disney films. As soon as I read Wesker I thought, wouldn't it be cool to have this military-type have a really cultured, chocolaty voice like George Sanders in The Jungle Book. Wesker is basically my version of Shere Khan.
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In an interview with Shinji Mikami Resident Evils producer, he claimed the game was originally going to be based around ghosts instead of zombies. He later changed it to zombies after being inspired by George.A.Romeros "Night of the living dead"
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Attachment There was an unreleased spinoff to the series called 'Resident Evil Dash'. It was supposed to be released between the first and second games, but got cancelled so it wouldn't hinder the development of Resident Evil 2. Ironically, that game ended up being delayed anyway. They ditched the original plans and started from scratch, which prompted them to appease fans by releasing a Resident Evil 2 demo disc with the Director's Cut version of Resident Evil 1. Dash was set 3 years after the first game in the ruins of the Spencer Mansion.
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Attachment Claire Redfield's jackets from Resident Evil 2 and Code Veronica contain references to the band Queen. In Resident Evil 2, her jacket says "Made in Heaven," and in Code Veronica her jacket says "Let Me Live." These are both song names from the band Queen.
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In Greek mythology Nemesis, Thanatos and Hypnos are all children of Nyx. In the Resident Evil series Nyx (Outbreak File#2) is an experimental Bio Organic Weapon, while Nemesis (RE3), Thanatos (Outbreak) and Hypnos (Survivor) are of the Tyrant line.
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There was once a project to create a Resident Evil game featuring ninjas. The game was to be set in a house filled with traps and hidden doors, much like the mansion in the first game but only set in Japan's Sengoku period. The characters were also supposed to be able to use ninja techniques. Eventually the project got turned into Onimusha.
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Attachment While Resident Evil has never actually tackled any supernatural threats and mostly just focused on scientific creations, there is one instance with the exception that confirms the rule. In the official Resident Evil Comics there's a story that takes place well before the whole Umbrella catastrophe. It features Jill and Barry investigating some murders in a college and ends up in Jill fighting off something that's supposedly a werewolf.
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