As I start tooling and gearing things up for my resurrected Imperium game using a modified Cephesus Engine, I’ve also had to start to codify some of what makes my setting different from the canon “Official Traveller Universe” (aka the OTU).
MTU and OTU are relatively common terms in the Traveller Grognard community btw.
First, my Imperium is way, way smaller than the canon Third Imperium despite using many or most of the same elements. It’s more like four-ish sectors in size, rather than the… sixteen-ish (???) of canon. I don’t feel like counting, but my size is based on a six-month travel time to the frontier (for Jump-4) and the actually spot my campaign is set is past that, in the equivalent of Honk Kong or Singapore or Macau. Basically on the bleeding edge of the Imperium, it’s six months by fast courier (Jump-6).
Sylea, the capitol of the Imperium, sits on the natural bridge that separates the Greater and Lesser Rifts, controlling a highly strategic location both militarily and economically.
The Ziru Sirkaa (the Restored Grand Empire of Stars) exists, having reconstituted itself during the Long Night after the collapse of the Terran Rule of Man. It is a trade partner and ally of the Imperium, though rivalries certainly exist.
The Imperium is not the most technologically advanced polity. They are simply the most widely and thoroughly developed overall. The Imperium is structured more on Napoleonic England than Classical Rome in many ways
The Solomani Confederation doesn’t exist. Terra and it’s environs is more akin to Middle East, in that is a resource-rich but heavily factionalized and conflict-ridden area with an often lower general technological base.
There is no Zhodani Consulate, instead the Zhodani Transhumans were the last great Imperial geeneering experiment during the Civil War. They fled the Imperium during the Psionic Suppressions and are one of the biggest of Imperial “boogiemen” but continue to fund underground psionic institutes and terrorist organizations inside the Imperium. Their current location is unknown.
Subsectors are 10×10 parsecs, a quadrant is a block of four subsectors, while a sector is four quadrants. Star systems are often somewhat farther apart than in the canon OTU, unlike the “mains” of most maps, though there are often clusters of systems together. Any given subsector might have two clusters of 5-6 systems, with a scatter of another 10-12 systems.
My setting primarily uses Collectors for powering Jump Drives, through for fast travel L-Hyd bladders are commonly used and easy to purchase at A & B starports that have a highport. Military-grade Collectors have the capacity for a “High Intensity” charge that takes only ~24 hours rather than the standard ~168, but carries some risk of damage. There are also a couple of techniques for similar speedy recharges that have related risks.
At least one race (the Sred*Ni) uses a biologically based technology for interstellar travel and Jumps from Gas Giant to Gas Giant. Some highly advanced races have developed much faster hyperspace drives, but the ship size seems to be much more limited. Rumors persist of races that have developed wormhole technology that allows then to essentially “fold space” and allow for instantaneous transport, but these are unproven.
The earliest Jump Drives (at Tech Level 9) are actually slower, rather than a parsec a week, the rate of travel is a parsec a month. This almost automatically involves low berths and cold sleep rather than awake and active crew, and an AI running things. These drives are still quite commonly used because they are cheap and are useful for non-time sensitive materials hauled by bulk freighter.
It’s a definitively “small ship” universe, as Tech Level increases, the ability to create Jump Drives that move larger and larger ships increases – though the Jump speed of ships is limited to the power of the computer installed indexed against the size of the ship. This is a shout-out to Book Two ship construction rules as opposed to Book Five ship construction. The maximum ship size at TL15 is 36,000 dtons, though these are limited to Jump-1.
Ship combat is based on Full Thrust rather than Traveller.
Navies and commercial ships are limited in number, not so much by ship construction requirements but by the psychological and physiological requirements of crewing ships. Simply put, the vast, vast majority of sophonts are not cut out for living in a tin can in space (another reason why travel is uncommon as well), not to mention for the penetration into and translation through Jumpspace. Theories abound regarding biotic fields or “the Traveller gene” but most people need some sort of drugs (or cold sleep) to cope with either or both for extended period of time. This simple fact is what keeps empires from fielding fleets that number in the hundreds or thousands, they simply can’t crew them.
At Tech Level 13, personal shields begin to be developed as an adjunct to contragravity. Useful, though expensive though problematic, they make piloting contragrav vehicles more difficult when active, and problem that is not solved until TL16. They also less efficient against energy rather than kinetic weapons. They are also limited in size due to power ratios, etc, not being able to protect a creature much more mass than a K’Kree.
Artificial Intelligence appears much earlier, starting at around Tech Level 9. The breakthrough at Tech Level 16 is that AI becomes able to Replicate itself with help (and despite hindrance), becoming able to self-propagate through the Datanet.
Cybernetics and augments are much more common than in the OTU, but not anywhere near as common as you would find in a setting like Cyberpunk 2020.
Laser Rifles and Carbines normally use capacitor packs rather than battery backpacks.
Parts of Known Space draw heavily from now decanonized Paranoia Press and Judges Guild source material.
Psionics, while still illegal in the Imperium, are more powerful than in the standard OTU.