Moongate

Moongates are magical doors made of moonlight, and are considered a fast, easy and safe way to travel through Britannia. There are four known types of Moongates, who's properties have changed through the ages, the most common being the naturally appearing blue Moongates, in addition to the artificially created red, silver and black gates.

Blue Moongates
Blue Moongates appear at eight places in Britannia, where the Moonstones are buried in the ground. Their function and destination is pending on the twin Moons Trammel and Felucca. Only very powerful artifacts, like Lord British's Amulet, can create a Blue Moongate somewhere else. The system of the Blue Moongates changed several time in the series:


 * The Blue Moongates were first seen in Ultima III. Back then, Trammel's phase decided which gate was open, while Felucca's phase determined the destination gate. The same system applied without changes to Ultima IV. Both Moons at the same phase either meant no travel, or at double Full Moon to the shrine of Spirituality.


 * In Ultima V, the system changed significantly. Now the moon highest in the sky determined the destination gate, and the Moongates only opened at night. The same applied to Ultima VI, but the Moonstones were stolen by the Gargoyles. When both Moons were at the same height on the horizon, the gate led to the Shrine of Spirituality.

Each Moon Phase is bound to one specific city gate:
 * By Ultima VII, the Sphere Generator of the Guardian disturbed the Moongates greatly in their function. One gate only led to the next higher one, and they were open all the time. In the end, the destruction of the Sphere closed the Moongates, ending their existence.


 * New Moon: Moonglow


 * Crescent Waxing: Britain


 * First Quarter: Jhelom


 * Gibbous Waxing: Yew


 * Full Moon: Minoc


 * Gibbous Waning: Trinsic


 * Last Quarter: Skara Brae


 * Crescent Waning: New Magincia

Red Moongates
Red Moongates are created with the Orb of the Moons, a very powerful and ancient artifact. They can lead practically everywhere, according to the Orb's placement and distance. With a Red Moongate, travel between Worlds becomes possible. However, the more distant the travelling destination, the more precise the placement has to be.

The first Red Moongate appeared in Ultima V, when Lord British used it to escape dungeon Doom; a little later, Lord Blackthorn left Britannia through another of this gates. In Ultima VI, the Orb of the Moons was used frequently and often, after the Avatar used for the first time a Red Moongate to travel to Britannia. In Savage Empire, a Red Moongate is used at the end to leave Eodon.

There are other Red Moongates that have been seen that may not have been directly created by the Orb. In Ultima VII, the Time Lord sent a Red Moongate to bring the Avatar to Trinsic. A Red Moongate also blocks access to the Sphere Generator.

With the destruction of the the Guardian's Sphere Generator, the Orb ceased to function, and no more Red Moongates were created. 

Silver Moongates
Silver Moongates, also known as Time Doors or Time Gates, are used for time travel. The destination to which time the gate will lead to is fixed for each gate, and can't be changed.

They are rare and unusual type of Moongate known to exist only in Ultima II, as a result of Minax meddling with time itself to destroy Earth. They vanished after the end of the game. They connected the following times:
 * Time of Legends
 * Pangea, 200 Mio. B.C.
 * 1423 B.C.
 * 1990 A.D.
 * Aftermath, 2112 A.D.

Although not appearing as silver, a Cubic Black Time Gate appeared in the first installment of the Worlds of Ultima series, The Savage Empire. This gate was an artificial creation of the Insectoid Myrmidex Queen in her plot to destroy her races one time masters, the reptilian Kotl.

In the second and final installment of the Worlds of Ultima series, Martian Dreams, another kind of gate was used for time travel. In this case, the Avatar travelled with Dr. Spector back in time to the year 1895 by way of electrical manipulation of the Avatar's Orb of the Moons using equipment found in Tesla's Secret Lab. The resulting gate was an unusual shade of bright orange, probably the silver of a timegate mixed with a red Moongate as the result of creating a timedoor with the Orb of the Moons. 

Black Moongates
Black Moongates are artificial creations that allow travel through space and time. They differ from other types of Moongates in that they are made not from lunar energy but are instead constructed from a mysterious substance known as Blackrock. They are not governed by Britannia's lunar cycles as are traditional Moongates; instead, Blackrock Gates must be powered by external power sources, such as planetary conjunctions like the Astronomical Alignment or Pagan's Titanic Objects.

The only known Black Moongate in Britannia was the Black Gate of the Guardian in Ultima VII, which was destroyed while the Guardian attempted to enter Britannia. Other known Blackrock portals were the Black Jewel found in sewers beneath Lord British's Castle in Ultima Underworld II, the Black Obelisk at Serpent Isle used by Batlin, the Black Obelisk of Pagan at the end of Ultima VIII, and possibly the Cubic Gate manifested by the the Myrmidex Queen of Savage Empire.