This mod introduces lots of changes ranging from the Netherlands to Poland and from Denmark to Italy. Many new provinces, cultures, historical countries for the 1444 start and formable or releasable nations (both historical and hypothetical), while staying mostly true to the original vanilla mechanics and the overall game balance, so you don't need to re-learn how to play the game as is the case with some of the overhaul mods.
This update works with the versions 1.17.x - 1.18.x of EU4, corresponding with the so-called Prussia patch. It has not been tested on the newest 1.19 Denmark patch (I'm planning a separate patch for that), so I'm not guaranteeing that it'd work for people who have it.