Hearts of Iron series

Hearts of Iron (abbreviated HoI) is a four-part series of global strategy games set in World War 2. The developer Paradox Interactive also refers to the genre as Grand Strategy.
The first part was released in North America in 2002 and in Europe in 2003, the next parts of the series were released in 2005 and 2009. The fourth part was released on June 6, 2016.
In the games, the player takes on one of over a hundred nations that existed at the time of World War II and guides them through the wartime.
They´re all good, but the fourth game is the best.
It is very complex and demanding, so you have to do read the tutorial.

Darkest Hour is the best HOI game, and 4 is for casu-els. Change my mind.

The newest HOI 4 version is one of the best games I´ve ever played.
Highly recommended!