Alternative history makes my skin crawl, but!!!!!!
The "1633" series by Eric Flint has some really hilarious scenarios! Here's the setup - an unidentified force lifts the relatively modern town of Grantville, West Virginia, into the middle of the Thirty Years War in Europe! So we have modern technology, U. S. ideas of government and social relations, gender, truth, justice and the American way...effectively changing the history of everything. Pretty soon the West Virginians have allied with Gustavus Adolphus, King of Sweden, and formed the Conferated Principalities of Europe, and making some really angry, really powerful enemies. This made me brush up on the European history of the 17th century. Yow! And fun.