SO, what is this "X-pack" about?
Jihadia, Trans-Sahelia and Bolivaria can create stealth drones, while the Federation can create attack drones.
Salviatia can create nasty "Silver Sphere" drones that look harmless until they open up and begin their attack.
The hovertank concept is a unit available to Salviatia and Bolivaria. Bolivaria gets the Huracan as mentioned, but Salviatia gets a unit with a name from Esperanto.
Exoskeletons and KBOTS.
Based off the Sectopods of XCOM these units are robotic units buildable to the Empire and the Federation. They start off as exos, then can be upgraded further into Kbots armed with heavy vulcans.
Suicide units that blow up killing armour instantlym and ripping massive holes in enemy formations. Available to Vidalia and the Horde.
Pit scorpions, fungiderms, giant snakes and voodoo warriors for Trans-Sahelia.
The Empire can create a massive flying warship that can decimate heavy units and cities with ease, but fails spectacularly against infantry and light vehicles.
Alien units such as the Handling Machine, Assault Tripods and Sentinel Tripods are available form various wonders.