Hearts of Iron II Doomsday is a standalone, complete version of the game that expands upon Hearts of Iron II, by increasing the time line to include the development of super weapons. Taking advantage of the huge gaming community, many balancing points and game play improvements have been included, enhanced by a significantly improved game A.I. The game also includes a complete scenario editor, so players can fully customize games of their own design, taking them to a whole new level of play.

• World War II scenario with an alternative historical outcome.
• Extended time line until 1953 with historical scenarios like the Israel conflict.
• Complete scenario editor.
• Expanded tech trees allowing players to develop tactical nukes and other types of nuclear warfare as well as helicopter squads, escort carriers etc.
• Enhanced Brigade Attachment system increases the player's tactical opportunities.
• Significantly improved AI.
• Tradable Weapons - equip your allies with the latest technological advances or get other nations to surrender their secrets.