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Mods are generally added to the Extensions in the game's route directory.
1.30: Mods can be subscribed to via the Steam Workshop.
Mods can also be found on the Nexus website.
An up-to-date list of many mods, and their status, can be found on the Egosoft's X Rebirth - Scripts and Modding forum here.
3.53: Loading order of mods (AKA "Extension ") can follow defined dependencies.
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