Although the Fallout series is vastly different from the world of Skyrim, one detail may show that the two do in fact share the same universe. Nirnroot, the elusive glowing plant that grows near Skyrim's water sources, has a doppelganger in Fallout 4 called Experiment NRT-0001, or «Glowleaf.» The two are almost an exact match, and though it's far from hard evidence that Skyrim and Fallout exist in the same world, it does open the door for it and raise some fascinating prospects regarding the possibility.
The world of Skyrim is known as Nirn. It consists of seven continents, but only one, Tamriel, has been the setting for the Elder Scrolls series. Fallout is a post-apocalyptic version of an alternate timeline of the real planet Earth, one where grotesque monsters like Super Mutants roam ruined cities. Skyrim follows Fallout's template closely, and the two have much in common such as running gags and various Easter eggs. Skyrim's Nirnroot — one of many alchemical ingredients players can utilize in potions — is one of them, though it may be tough to find. It might sound like the two worlds being one and the same is implausible, but it might not be as much of a stretch as it seems.
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Bethesda VP of Marketing & Communications Pete Hines has specifically stated that Fallout and Skyrim are two separate worlds, and though this may seem like it disqualifies any such theories, there's still the possibility. He is not a developer or creatively involved with either series, so his word alone does not eliminate the idea that the various protagonists of the Elder Scrolls and Fallout games walk upon the same earth. It's possible that the developers even have their own ideas on the subject
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