The game play for Perimeter: Emperor's Testament is consistent with classic RTS movement. You select your units, provide commands, and give them a place to go. But that is just the surface. There are some really cool and well balanced features. Your main base is a movable city called a frame, with hundreds of lives on board. In order to build, you need to have a solid foundation. You control terraforming machines called "brigadiers" that go forth and convert the land to your desire. You simply select the area you want with the mouse and a free form pointer tool. Everything you build on the ground has to have some form of power for it. You end up building chains of "Energy Cores" and relays to provide power to your structures and defenses. When threatened, you can activate shields that encompass the perimeter of your area. This shield surrounds your entire perimeter, hence the name of the game. Everything you build is determined by the amount of energy you have, so be aware not to run so low that you can't use the shields.