The Gray Faction is the fourth faction in the game and can be unlocked after researching UFO in the Laboratory. However, it also costs a lot of Starbux if you want to actually finalize the switch. You can also switch back to your faction you chose at the start at any time as well if you are using a Gray Ship (With 1 Hour Delay).
The Gray ships are incredibly diverse but they usually all have an easily armorble horizontal design. This makes it great in high level combat. The main thing that stands out is the Gray's switch cost, it costs 2.2K Starbux to switch to the Gray Faction.
The main color scheme for the Gray ships is their obvious alien appearance and use of green and grey.
The List of Gray Ships can be found here Gray Ships.
Gray • Visiri