The Gray Faction is an additional faction that can be unlocked for all factions, regardless of type. The Gray Ships are unlocked after researching UFO in the Laboratory and will become purchasable for 2.2k Starbux in the Shipyard. After purchase you are able switch between your starter faction and the Gray Faction, free of charge. (With 1 Hour Delay).
Early on the Gray Ships are insignificant to the other factions requiring multiple Lifts and poor Armor/grid effectiveness. Later on it develops a horizontally-sound rectangle and becomes more efficient with Armor, similar to the Pirate Faction. In combat you will find your Crew trekking longer distances to get between room to room, as trade-off to its easy layout setup and higher armor potential. Overall a great middle ground for advanced combat.
The main color scheme for the Gray Ships is a rustic brown with a mix of metallic gray/lime, and faded green secondary color highlighting your typical alien craft.
Gray Ships information can be found at: Gray Ships.