The Alien General minifigure has a Dark Stone Grey body, legs and medium stone grey arms, and purple hands. It has armour printing on its torso and legs. It has back printing on the helmet and torso armour. The head is gold and depicts a face/mask. It is able to carry a gun. It has different printings than the Alien Foot Soldier.
Loki was given the Chitauri army by Thanos to help him take over the Earth and become king in exchange for the Tesseract. Loki had Hawkeye and Erik Selvig build a portal machine to bring the Chitauri to Earth, using Stark Tower as a power source.
The Chitauri then attacked New York City and fought the Avengers, which includes Hawkeye , Black Widow, Iron Man, Captain America,The Hulk, and Thor. They used spaceships, bombs, and blasters. The Chitauri were defeated when Iron Man sent a nuclear missile through the portal which destroyed the mothership, causing all forces on Earth to shut down. The portal was then closed by the Black Widow by using Loki's scepter.