Traveller has 15 listed Tech Levels (TL) and allows for the possibility of higher TLs. It, being a game of sci-fi game of space adventure in the far future, reaches far into the future at the higher tech level, with all of human history being TL 7 and lower. Below is the Tech Level table from Mongoose Publishing's Traveller.
One of the first things we need to ask is "what's the design reason of TLs?" In Traveller, they determine relative power ranks for what types of weapons, armors, vehicles, vessels, and other equipment exist. Basically, the "material stuff" that occupies the game realm. This means that TLs play an integral role in the "treasure" aspect of the game. They're about stuff, and stuff is what players like to gain
TL 0: (Primitive) No technology.
TL 1: (Primitive) Roughly on a par with Bronze or Iron age technology.
TL 2: (Primitive) Renaissance technology.
TL 3: (Primitive) The advances of TL 2 are now applied, bringing the germ of industrial revolution and steam power.
TL 4: (Industrial) The transition to industrial revolution is complete, bringing plastics, radio and other such inventions.
TL 5: (Industrial) TL 5 brings widespread electrification, tele-communications and internal combustion.
TL 6: (Industrial) TL 6 brings the development of fission power and more advanced computing.
TL 7: (Pre-Stellar) A pre-stellar society can reach orbit reliably and has telecommunications satellites.
TL 8: (Pre-Stellar) At TL 8, it is possible to reach other worlds in the same system, although terraforming or full colonisation are not within the culture’s capacity.
TL 9: (Pre-Stellar) The defining element of TL 9 is the development of gravity manipulation, which makes space travel vastly safer and faster.
TL 10: (Early Stellar) With the advent of Jump, nearby systems are opened up.
TL 11: (Early Stellar) The first true artificial intelligences become possible, as computers are able to model synaptic networks.
TL 12: (Average Stellar) Weather control revolutionises terraforming and agriculture.
TL 13: (Average Stellar) The battle dress appears on the battlefield in response to the new weapons.
TL 14: (Average Stellar) Fusion weapons become man-portable.
TL 15: (High Stellar) Black globe generators suggest a new direction for defensive technologies, while the development of synthetic anagathics means that the human lifespan is now vastly increased.
The second question is "Why so granular?" There are 15 listed levels, why not 7 instead? The reason, of course, is to provide a wide range of possible stuff, especially when creating science-fictiony stuff that doesn't actually exist. It allows the stuff in the game to have a wide range of power. This makes for more mechanically interesting options. It also allows for at least the appearance of greater diversity among locations.
Now we run into our first problem in creating a fantasy game from the Traveller rule's set. Were I to use the RAW (rules as written), I'd end up with only TLs 0-3 for Worlds Apart as I want it to be a fantasy game, not a tech-fantasy or science fantasy and I'd end up losing all the advantages I just listed in having a many step range.
Its these two answers that leads me to create a TL chart for World's Apart that is in the same style as that in the rules from which it is spawned, but of simply lesser technology increments. Below is the TL chart from Worlds Apart.
TL 0: (Primitive) No technologyYou'll note that I've chosen to extend all the way into the Early Industrial. This means that there are locations out there resembling the early-early/mid 1800's (sans gunpowder and explosives, of course - this is fantasy.) I've put in the (Primitive) to indicate to Traveller players that all of these TLs are TL 0-3.
TL 1: (Primitive) The Middle Paleolithic
TL 2: (Primitive) The Upper Paleolithic
TL 3: (Primitive) The Neolithic (agriculture begins)
TL 4: (Primitive) The Copper Age
TL 5: (Primitive) The Early Bronze Age
TL 6: (Primitive) The Late Bronze Age
TL 7: (Primitive) The Early Iron Age
TL 8: (Primitive) The Late Iron Age
TL 9: (Primitive) The Early Medieval Age
TL 10: (Primitive) The Late Medieval Age
TL 11: (Primitive) The Renaissance
TL 12: (Primitive) The Age of Sail
TL 13: (Primitive) The Very Early Industrial
TL 14: (Primitive) The Early Industrial
Well there you go. The first in what is going to be many installments about the game and my thoughts about its design. The TL table for Worlds Apart. If you have any thoughts or comments, please post - all of this is far from being carved in stone.