Allohistory

But some discussion of the complex relationship between “allohistory” and sf is appropriate here, as the genres overlap in certain ways. Classical allohistory— such as Trevelyan's "What if Napoleon had won the Battle of Waterloo?" and Churchill's "If Lee had not won the Battle of Gettysburg" —is a rigorously consistent thought-experiment in historical causality.

Source: wiktionary

[…]the early twenty-second century in a timeline where the atomic bomb that instilled such dread in Royland never materialized, resulting in an Axis victory. Over fifty years old now, "Two Dooms" predated Philip K. Dick's more famous World War II allohistory, The Man in the High Castle by three years.

Source: wiktionary

I define alloliterature as the alteration of known literary texts to present an alternate outcome from the original text. As with allohistory, a large range of texts can be deemed alloliterary in nature, with the three primary types of alloliterature aligning with the three types of allohistory:[…]

Source: wiktionary