Paradox Interactive has released patch v1.4 for Hearts of Iron 3, fixing bugs and adjusting features to address fan concerns and feedback in the World War II strategy game. The update is available from all digital distributors that carry the title.

AI has been improved in all areas, with special attention paid to cooperation with allies and production. Work has been done on optimization, and the game is now more than 30% faster than v1.1, and numerous interfaces are now much quicker to access, reducing lag. Land, air and naval units have been rebalanced to improve the overall game experience, and more support for user modifications has been added.