The game also includes abstracted rules for ground combat. Terran land units are green while Imperium units are black. In addition to regular land units and planetary defense units that can oppose a landing, there are special drop troops that can land on a planet without requiring a ship to transport them to the surface. If one side is all standard troops and the other side is all drop troops, the standard troops gain a bonus artillery attack against the drop troops to simulate the inability of the drop troops to carry a lot of heavy vehicles with them. The ground units have a single combat factor, plus a symbol and a unit identifier. Surface combat used a combat differential with the defense combat factor subtracted from the attacker's combat factor. A die is then rolled to determine whether the unit is destroyed.