To be honest I'd recommend something self-contained with a good chance for conclusion. Europe in any age is something on a grand scale and there's very little chance for proper conclusion. Internal power struggles on the other hand are something where a conclusion could be in sight. Civil with several parties could be very interesting. A very interesting idea could be the Russian Civil War(1917-1921), due to the involvement of several sides and loose coalitions. Add to that foreign involvements and you might have a potentially very fruitful scenario. That said it would be a very ambitious idea research-wise and add to that the fact that we're dealing with a time far more complicated than 16th century Europe and you have a lot of work on your hands. There's social, political, military and economical factors at play, which could make prediction very hard work.