This is a new take on the traditional Starcraft races. The three races have been replaced by three hybrid races. The Bionics, the Infested and the Void Predators.
Me (yellow) building a defense for the expansion base of an ally AI player. You can see two different towers in this image; 1 is the energy cannon that is similar to Photon Cannons and the other is the Fusion Cannon. Fusion Cannon are advanced towers that can only target ground units and are expansive but deal heavy damage at decent range.