Recently, when I was playing the adventure "Book of Unwrittten Tales", that hero gnome Wilbur went into an inn where two Persons spent their time playing a "fantastic multiplayer adventure", with an unique setting in a truly fantastic world. They were both occupied to pay their taxes for the year, to maintain the bike one of them owned, and to work for a living.
Fantastic, IF you are a creature from a fairytale-world. Boring, if you aren't.
It is the same with MoO3. I did not own any other parts of the series when I bought this game back in 2003, but I had enjoyed playing Ascendancy and Imperium Galactica 2, and was looking for a worthy successor ever since.
BUT MoO3 is not a game. It is an overwhelming self-sufficient universe-simulation, in a sense, that nothing you can do will have a significant influence on that universe. This game does not need any player. If you try to influence anything in this universe, you feel like Don Quixote fighting windmills, or at least, like an subaltern city administration employee sitting in front of a desk with piles of paperwork, waiting to be done.
IF that sounds fun to you, give it a try.