Energy is a global resource across all your buildings, but materials are local to each one. Damaged units lie in one of my shops awaiting repair and rearming. The combat system is simple - each unit has a maximum strength of 10, and can lose strength in each attack. Each attack is resolved with a splendid automatic 3D view of the encounter, but to see this smoothly in full detail you need a Pentium. It is worth it though.
Different terrain can affect combat, as can different weather conditions.
Some units can build defences for increased protection. A number in brackets is the weapons' range in hexes. Given the importance of experience, any enemy unit you damage with multiple attacks should be finished off before it can escape for repair. The transport ships can each hold many robot units. Given a fast enough machine to run on, everything is quite slick.