Arsenal of Democracy, a grand strategy wargame based on Hearts of Iron II, was released in February 2010.

The player can build land divisions, aircraft squadrons, and naval ships/fleets, and combine these into corps and armies.

The player can choose to play almost any nation from the time period, apart from some very small states such as Andorra, Monaco, Vatican City or others (and mods exist that make even these playable).

The smallest independent land unit is the division, although brigades such as engineers, artillery, or armoured cars can be attached to these.

Sea units include transports, aircraft carriers, battleships, cruisers, destroyers, and submarines.

Paradox has stated that it will not reduce the level of historical accuracy in order to appease the PRC censors.

The game can be easily modified by users to include such graphics, but Paradox disallows discussion of this particular type of modification on their message boards.

[11] A stand-alone expansion pack to the game, Hearts of Iron II: Doomsday, was released on April 4, 2006.

Doomsday also features some other changes and additions such as: Another expansion was released in April 2007 in an alternate history scenario called Hearts of Iron II: Armageddon.

It allows the adding of modules to ships (such as improved radar, fire-control, anti-submarine or anti-aircraft weaponry) and submits two new scenarios for play, as well as an enhanced AI.

It expands the number of provinces on the map as well as numerous other additions and can also be installed as a compatible expansion of Arsenal of Democracy and Darkest Hour.

[17] On Metacritic the following reception was achieved by Paradox Development Studio: GameSpot gave it 8.3/10, writing that "this is what the original game should have been".

[13] Hearts of Iron II was a finalist for PC Gamer US's "Best Real-Time Strategy Game 2005" award, which ultimately went to Age of Empires III.

[18] It was also nominated for the 2004 Charles S. Roberts Award for "Best 20th Century Era Computer Wargame", but lost to Battles in Normandy.