You start with 6 armed units and some medibays. These used power, and over time resources are dropped that must be collected to maintain the power levels. There are also other factors that make life harder: meteors will randomly crash into the moon starting fires which must be extinguished. In addition, enemy invaders will attack your base and must be repelled.
The layout of the moonbase is randomly generated each time to give each game variety, and there's loads of tension as you send out a unit to collect resources outside where they are exposed to attack. It's a great game if you've got a spare 5 minutes, and completely free!
