I see an issue with Lithuania here, it seems overpowered. It becomes a large empire and has vassals and such, and expands deep into Russia and Poland. In my latest game it had Poland and Moscow as vassals and was very large.
Lithuania was huge! Before Muscovy expanded eastwards (this is after annexing the Kingdom of Novgorod) and before Lithuania was gobbled up by Poland, Lithuania was one of the biggest and most powerful countries in Europe.
What date were at when you made this post. If you are around 1300 to 1600 it seems about right. Muscovy and Poland have to "beat up" Lithuania afterwords.
Lithuania in 1500
