In a submerged world, the man with the oil is king. He is the one who controls the flow of a battle. In Unigine's game, making mad grabs for oil derricks is something that you absolutely have to do, and that it ties into the theme so neatly is admirable. You send out your units and they grab. Derricks, nodes, factories, helipads. It's all quite elegant. It just took me a little while to figure out why.