EU4 is a strategie game able to be played in single- or multiplayer mode. You have a timeline from 1444 - 1812 to play. Your main quest is to expand your country with war, or diplomatic actions. You can hire soldiers to fight, get mercenaries or just a bunch of diplomates. But you have to find a good balance between war and diplomacy, because other countries will get aggressive expansion, when you conquer some land. The world is split into provinces. Every province has it’s one type of region, and things they produce. And of course, not all provinces are the same, some are better developed, the other one produces spices, the other salt, this province has more inpact in trading then the other province, … . The best thing to do, would be to just try it!