If it is, how would I do it? Mostly for mods, but id like to be able to easily switch version.
#Is it possible to add an older version of factorio to the mod menu?
thin aspen
strong wave
factorio doesn't work like that. if you want to have multiple versions, just download them off https://factorio.com/download/archive/
Make double sure to download the zip version for hassle-free self-contained version! By default, the installer will use the same data folder as your steam version.