It is a world where the sky has become uninhabitable, everyone has dug underground and now the battle for viable resources has begun. Use your digging base to create paths to send units and scouts down, and collect valuable minerals. As you collect more minerals you can then deploy more units of a variety of shapes and sizes. Use them to beat back the opponents in the underground that are trying to get all of the resources before you. After they have laid claim to all the resources, they will then destroy you so that you are no longer a threat. Fight back before that happens and kill them before they can kill you.