The Hearts of Iron III Collection includes the HOI game and all its DLC, which means you get the base game and then all the additional scenarios.

A mix of Total War and Risk

The Hearts of Iron III Collection has elements of Total War and Risk in that you conquer different locations and then farm them for resources while pushing your other troops forwards. The micromanaging side is a little similar to the Civilization 3, 4 and 5, but the consequences of your micromanaging are less obvious. To fully exploit the game, you need to learn a lot about how it works and what each metric means, which means you need to literally invest hundreds of hours into the game to both learn about it and then complete it.

A game for the dedicated

The Hearts of Iron III Collection does have a few problems, with the most obvious being that it is not newbie friendly. It was built for fans of the HOI franchise because it is a complicated game that doesn't explain itself very well. Even the tutorial misses some very basic elements and feels unfinished. The other problem is typical of these strategy games in that the AI doesn't manage your assets correctly. Many times you will find yourself handing control over to the AI only to have to take it back later because your asset is costing more than it should be.