Call of Duty: World at War is considered the hardest game in the series, with intense enemy presence, constant fire, and challenging missions that make it the ultimate experience in terms of difficulty.

Heart of the Reich is the most challenging mission from the most difficult Call of Duty campaign, World at War. This mission, especially on the Veteran difficulty, is a nightmare for many. The Russians have fought back the Germans and are taking the fight back to the Germans, the heart of the Reich.