Even though Bethesda has not yet released the official modding kit for Fallout 4, there are a whole host of mods already out. Some attempt to fix the various issues with the game, such as dialog wheel; others try to make the game easy by bypassing systems which make no sense, such as the encumbrance limit. others try to make the game prettier, or run better.
Then there is this- the Really Useful Fallout mod replaces a whole host of things in the game with a Thomas the Tank Engine model. This includes Deathclaws, Vertibirds, Liberty Prime, and things such as missiles- just for starters. Effectively, this mod makes Fallout 4 the game it was always meant to be, painting a bleak picture of a post apocalyptic wasteland, where humanity struggles with its own nature in its quest for survival, fighting against the human condition, the elements, and a world populated by Thomas The Tank Engines.
