Big 3 is played over a map of Europe and North Africa. The game map is superimposed over a hexagonal grid of eighteen rows and eighteen columns, for a total of 324 areas. Each area is about 200 kilometers in diameter. The terrain includes capitals, factories, and ports. Capitals and factories have economic values.
Ports are only places for ships to dock and for invasions to be conducted.
Players maneuver and engage their forces in combat, one front at a time, using the boundaries or western, eastern Europe and the Mediterranean. Frontal options are either offensive or tactical operations. Units are moved one at a time, with no stacking of land units allowed except for paratroops. Combat occurs by attempting to move units into enemy-occupied terrain. Ships, planes and armies all move the same way by gaining control of an area by simply moving an infantry or armored unit onto it.