The basics of My Traveller Universe
Pretty much a vanilla clone of the OTU (Original Traveller Universe).
Start date is 1104, a year before the 5th Frontier War, so giving us some play time before anything major happens.
The Imperium is a vast feudal system, mostly harmless, neither good nor bad. Among the 11,000 worlds it controls, some are good, some are evil. It is still a feudal style system, run by the nobles. While a few are elevated to nobility for various deeds, most of the actual ruling nobles are hereditary. There are a lot of bureaus and groups in the government, some highly competent, some not so much. Pretty much reflecting our world.
Technology is as per Classic Travaller mostly: the shotguns in space is still a good description. Energy weapons are available at higher tech levels, with varying degrees of power requirements. There are no force fields, tractor beams, light sabers - this is not Star Trek or Star Wars. Psionics are possible, but I keep with the Imperium's distrust of those with mind powers. I also use Classic rules for those, so they are not particularly useful.
Everything is still speed of jump: a jump can cover 1-6 parsecs per week. Larger jumps require larger amounts of fuel: 10% of ship volume per parsec. So high-jump craft don't have as much space. Communication between systems is via ships carrying the messages. The X-Boat route is of more historical than current relevance: while still used, there are enough other ships moving about that sometimes it may be faster via private courier.
I run a small ship universe. There are big ships out there, but they are not as common. Ships are still expensive, but there are a lot. I'm leaning towards GURPS Traders for ship traffic - even if they are expensive, they do last a long time. Ships are tough.
Computers and communications are more up to date than Classic - going with Mongoose or T5 rules probably. True Artificial Intelligence starts emerging at TL 14 or so, but until then it is more a very good simulation. Robots are not particularly common or uncommon - not nearly as common as Star Wars, but more of a background sort of thing. Think of Roombas.
I'm not a gearhead, so I won't be detailing a lot of the ships, vehicles and things out. While I do like Classic High Guard for ship designs, things will work at the speed of plot for the most part.
Within the Imperium, the credit rules. I've basically a tamper-proof Imperial credit card so that transactions are easier to deal with. Outside the Imperium, credits may or may not be accepted, and cash is king there. More likely it will be trading goods or services to get things purchased. So try and plan ahead: you may not be able to eat on the next world unless you bring along cold, hard cash. Gems, rare metals may not be worth anything either, so some initial research may be needed.
As for languages, most systems speak Anglic. A few die-hards still speak Vilani. Universal translators do exist, and get better at higher tech levels. But only for known languages: a completely unknown language will take time to learn even with machine intelligence.
Standard aliens (Aslan, Vargr, Droyne, Hivers, K'Kree) are all there, along with a multitude of minor races. This is mostly a human-centric universe, at least in the Imperium. But strange new worlds are out there.
I'll be using mostly Mongoose 2e rules, with a smattering of T5 things in there.