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The 1.02 patch, released on Novem added four new grand campaign scenarios and new functionalities (infantry units can now have two brigades and it is possible to upgrade a unit to a different model, for example, a simple infantry unit can be upgraded to a motorized unit). The game provides a launcher that allows the player to change its settings (like resolution, language, etc.) and eventually choose a mod to run on top of it. All this is on a global scale, with the player simultaneously dealing and interacting with nations across the world. Technological research is also controlled by the player. Moving the sliders would result in different bonuses and penalties, allowing for a range of choices and strategies. The player can also alter the social and economic policies of their nation using sliders, such as democratic versus authoritarian, free market versus central planning and so on. The player can declare war, make alliances, claim and annex territories. The player also has the ability to control the appointment of military leaders of land, air and naval units as well as to control the appointment of individual government ministers and military commanders in key General Staff positions. The player can build land divisions, aircraft fleets, and naval ships/fleets, and combine these into corps and armies.
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Moreover, the most important changes to the engines have been added as mods to the core game, with the name Darkest Hour Light and Darkest Hour Full: This has been considered crucial by the development team to make it easy to port community-made modifications from Hearts of Iron II to Darkest Hour. Darkest Hour is, at its core, an evolution of Hearts of Iron II: Armageddon.
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