Downfall is a two-player game on the conquest of the Third Reich in World War II. One player controls the Western Allies and the other the Soviet Union in their joint effort to destroy the Axis. Though the two players share the goal of defeating the Reich, each seeks a victory that favors their dominance in post-war Europe. To this end, each player controls two factions:

• The Western player commands the Western Allies faction and the OKH faction, that is the German and minor Axis armies battling the Soviet Union in the east (Oberkommando des Heeres).
• The Soviet player commands the Soviet faction and the OKW faction, that is the German and Italian armies facing the Western allies in the west (Oberkommando der Wehrmacht).

Gameplay is driven by Downfall?s innovative initiative track. The faction with the initiative chooses an order, pays its initiative cost by advancing their marker along the track, and performs the order. Then, the faction with the initiative (based on the updated positions of the markers) chooses the next order. There is no set sequence of play; initiative expenditures determine who goes next. The progress of faction markers along the track also trigger strategic events, changes in weather, and advancement of game turns.