Unit

A unit is a vehicle created by the player or an alien which can be controlled. There are multiple types of units.

In Planet X1
The player has only 2 tanks, and they cannot be built again if they get destroyed. Tanks and enemy spiders are destroyed immediately when they drive into lava.

In Planet X2
In Planet X2, there are two types of units, and they can be built using factories. The unit types are builders and tanks. Player units cannot go over water, while the alien Protoids can at a reduced speed.

In Planet X3
In Planet X3, units can be built using factories.