Hearts of Iron III: Their Finest Hour puts you back in the commander’s seat during World War II. Win the war with new units, strategies and enhanced game modes. Destroy your enemies from within with an expanded espionage system that includes new missions and covert operations. A new battle plan mode allows you to load historical plans or draw your own; all of which can be shared with allies in real-time during multiplayer. Along with the enhanced gameplay there are two new battle scenarios and a new custom game mode that lets you jump straight into the action.Go to: http://store.steampowered.com/ and download STEAM client
Click “Install Steam” (from the upper right corner)
Install and start application, login with your Account name and Password (create one if you don’t have).
Please follow these instructions to activate a new retail purchase on Steam:
Launch Steam and log into your Steam account.
Click the Games Menu.
Choose Activate a Product on Steam…
Follow the onscreen instructions to complete the process.
After successful code verification go to the “MY GAMES” tab and start downloading.