The world screen shows available levels and what vehicles can be used. Big circles are main levels and little circles are training and bonus areas. The objective of main levels is to clear a path for the carrier that contains the nuclear missiles to safely travel. If it runs into a building or you hit it with a vehicle, then it is game over. Along the way, you can light up Radiation Dispersal Units (RDUs) by driving nearby them and rescue survivors by destroying buildings. Some levels may have hidden communication points that unlock additional levels. Once a main level is completed, you can play it again to destroy any remaining buildings and find all RDUs and communication points.
Rank[edit]
You receive gold, silver, or bronze commendations for completing levels based on performance. Each main level rewards a gold commendation for clearing a path and second one for destroying everything and collecting all survivors and RDUs. Other levels reward a commendation based on time. Gold commendations are worth 3 rank points, silver are worth two, and bronze are worth one. A rank is awarded for every 12 rank points collected.