Oberth
Oberth is perhaps the most sought-after of all lost worlds, definitely the most fought-over. Oberth was a round world in a Finite Dimension whose orbit took it through all seven known Domains. This meant that depending on the time of year it was very easy to jump to any known dimension. Oberth first became an important hub for trade and travel, then later on as a staging area for invasions. An army transported to Oberth could be landed anywhere in the Known Worlds for a fraction of the effort of launching from anywhere else.
As such, Oberth became one of the most highly contested battlegrounds of the Mage Wars, changing hands constantly throughout the Dynastic Period.
History
The earliest-known mention of Oberth in ancient documents dates from about B.G.A 3600, approximately 200 years after High Tower. These documents reference a perfectly mundane Waystone changing hands for a sum of gold, an expensive purchase at the time; but this is the earliest confirmed reference to Oberth. It is believed the planet may have been discovered over 100 years earlier and already formed a key part of the Waystone Network. It was known by several names during the First Chaotic Period, so fixing exact details is challenging.
Over the next century, dozens of historical battles and campaigns are thought to have taken place on Oberth. None of these resulted in the total conquest of the world, but many early Tower empires held territory on Oberth in order to facilitate trade. While competition for control of the planet was fierce during this era, it generally focused on the strategic importance of the trade and travel hub.
The whole of Oberth was first concurred in B.G.A. 2506 by the Marcon Alliance, solidifying their position as the most powerful multi-world empire. According to legend, the planet changed hands 99 times (roughly once a year) over the course of the Intermediate Period, mostly between the Marcons and M'KHara.
By the Dynastic Period, the battle for Oberth became more about denying its use to anyone else than actually controlling it, though many major campaigns would still use it is a staging area. Oberth is also famous historically for receiveing the last new Waystones, built in secrecy sometime during the Dynastic era.
Exactly how or when Oberth became "lost" is unknown. Most historians believe Oberth was either destroyed or rendered uninhabitable sometime at the very tale end of the Dynastic Period. However, accounts persist through the Second Chaotic Period of Wayshifters still using it as a stopping point as late as B.G.A. 100.
Later History
In A.Y. 151, a man named Lars Philpot arrived in Arindell claiming to be a Wayshifter with the ability to travel to Oberth where he claimed "vast riches littered the very ground". Some believe Lars had Oberth confused with Megareth, which was very much not lost but quite dangerous.
Physical Location
One complicating factor is that while Oberth is known to have been a round world orbiting a star, no one has ever been able to definitively identify which Finite Dimension it is located in. The World is the most likely candidate, but finding it there is akin to a needle in a giant stack of needles.
If Oberth could be found and any reasonably-sized portion of the planet still exists, it could be re-terraformed and restored to use.
Fringe Theories
Because of the timing of Oberth's destruction, there is outsider speculation that it was conquered by the Gudersnipe Foundation and now forms the heart of the GATE network. These theorists further speculate it is located within the Utops Cluster and this is why the Foundation built its primary stronghold here. The Foundation has never commented on this, however it has expended significant resources over the years in locating Oberth for "its cultural, historical, and potential economic value".
