A major marketing point of the series, the game allows for things as big as the USA having a revolution in response to the Great Depression (you can choose whether to become Socialist, Fascist, Communist, or something else), to events as small as a historically-neutral country joining a certain side (Spain/Turkey/Argentina/Portugal joining the Axis or Allies, Brazil joining the Comintern, the USA joining the Allies before Pearl Harbor, etc).

Aces themselves are tiered, with the basic one representing what Ace Pilot is in Real Life, while tier 3 comes with Improbable Piloting Skills, Improbable Aiming Skills and make the entire air wing perform as if it was fitted with lesser aces. Ace attached to an air wing increase its performance in specific missions.

Ace Pilot: In IV, there is a chance to generate those during air engagements.

Acceptable Breaks from Reality: Many of the political focuses in IV such as Britain turning fascist/communist, Trotsky returning to USSR and Germany returning to monarchy would've taken Alien Space Bats to succeed post-1936, but are featured in the game because it's more fun to give players more alternative scenarios and modeling political events beginning in the year 1920 would be extremely difficult as well as demanding on hardware when the game is known to have problems with just reaching its 1949 end date on acceptable frame rates.

This video game series provides examples of: The games have a large modding scene actively encouraged by the developers some of the more prominent of those can be found here. West, a planned spin-off set during the Cold War, which was canceled.

Hearts of Iron: The Card Game (2011) which uses the series name and is based on World War II but has little else in common.

A forthcoming DLC, No Step Back, revamps the focus tree for Poland and USSR as well as adding new content for Estonia, Latvia and Lithuania, in addition a revamp of the logistics system and the addition of Tank Designer.

Darkest hour hearts of iron mods