Historical games are set during real historical periods, though may be based on fictional or fantastical events. Those which diverge greatly from history are best described as fantasy, though mythical might better describe a setting such as Ars Magica where a close eye is kept on historical reality (despite the existence of magic).

However, historical settings provide a wide range of backdrops for all types of genres. The original Cthulhu stories would today be regarded as historical - mostly 1920s America. The Baroque Cycle or the Hornblower series are also historical, the former with a touch of fantasy.

The type of technology and skills available to characters in a historical period are defined by the setting's Technology Level, which ranges from 0 (stone age) up to 8 (modern day) or higher.

The Stone Age can be difficult to built an RPG around. Skills would be limited to survival, hunting and crafting with not much else. Shamans may have some 'mystical' powers (which may be little more than headology, and a good knowledge of nature) but society isn't complex enough to have a wide range of character roles.

In terms of years, this is the largest period covered, spanning at least hundreds of thousands of years. It ranges from the first stone tools used by cavemen through simple hunter-gatherer societies living in grass huts to the beginnings of agriculture.

Though there is a (relative) wide range of technologies available during this period, it is rarely gamed except in time travelling or SF campaigns where PCs crash on some primitive world. As such, everything is rolled into a single TL.

The main feature of this period is that it pre-dates the manufacturing of metal working. Agriculture may exist, though it is on a small scale and not particularly common, restricting the size of settlements.

Covers the period from about 3000 BC to around 700 BC in Europe (or earlier in the Far East), and stories set in such a period will be set in the earliest cities. The Bronze Age sees the rise of agriculture, the building of cities and long term social structures not present during earlier periods.

Unlike the Stone Age, there are plenty of story opportunities for characters, from politics to war and adventure.

Technological skills will not be available, and knowledge of the world will be shaped by superstition. There are plenty of cults to add flavour to such campaigns.

As with everything, reality has a habit of confusing things and some cultures should possibly be considered TL 1 even though they lack metal working. Many South American cultures had complex city states, mathematics and even rudimentary technology without discovering metal working.

The Iron Age sees the rise of the Roman Empire, Egypt and the Far East. Changes from the Bronze Age are incremental as far as stories go, with better communications over larger distances, and bigger buildings and cities allowing for more complex city based campaigns.

Historically, the Iron Age is defined as ending with the rise of Greek and Roman societies in the Mediterranean and equivalent trends elsewhere. The Early Middle Ages (after the collapse of the Roman Empire in Northern Europe) is defined as the end of the Iron Age, however this period is still classed as TL 2 due to the collapse of urban centres.

Probably the most common period for fantasy campaigns, it is mostly dominated by the rise of monotheistic religion and the domestication of the old tribal groups in Europe. Travel is still limited, and weapons and armour are getting better, but don't differ greatly since earlier periods until late in the Medieval.

It does of course see the rise of the Knight, at least in Europe, and the ideals of chivalry.

The later Roman Empire can also be considered TL 3, bordering on TL 4. It had great cities, organised armies and a complex trade and social system. In terms of society, culture and organisation, it was TL 4. It terms of science and technology it was TL 3.

From about 1450 onwards in Europe, the Renaissance saw the birth of science and modern technology. The advent of gunpowder weapons, art, culture and trade all combined to form a political environment not seen before.

Money, not breeding, was beginning to be seen as an important symbol of status, and new horizons were being opened up in the New World and Far East. By making characters merchants, or part of a merchant's retinue, adventures can cover politics, war and adventure with equal ease.

Skill sets are similar to the medieval period, with Natural Philosophy still being used instead of Science to understand the world. Cities are growing big enough, and complex enough, to easy set whole campaigns in a single one, and are suitable for Thieves World or Farfard and the Grey Mouser type stories.

If the Renaissance was the birth of Science, so the Enlightenment is its coming of age. Yags treats periods prior to TL 5 (assumed to be early 18th century) differently to those that come later. Before TL 5, knowledge about the workings of the world is treated with the Natural Philosophy skill. From TL 5 onwards, Science becomes available and provides access to Physics, Biology and Chemistry as separate skills.

Exploration, politics and war are all respectable past times for PCs. This is also a good age to add in various alternative technologies - steam punk for example.

From the late 19th century to the end of World War II, the Mechanical Age covers the rise of the machine and industrialisation on a global scale. Science is here to stay (we hope), cheap air and sea travel become a reality for adventure in distant lands, and there's even ready made bad guys in the form of the Nazis.

Except for the type of equipment available, there's very little difference between TL 6 and the modern day unless you are looking at scientific and technical skills. It is a good period for pulp style action adventures. Much of the world is still unexplored (from a European perspective), the rise of Nazi Germany provides a convenient bad guy, and communication is difficult, making it easy for PCs to be cut off form support and aid, forcing them to survive on their own abilities.

From the 1940s to the 1980s whole new areas of science began to open up. Human space travel became possible, though this was based on the rocket technology of TL 6. Micro computers were a big change from the old vacuum tube designs, and began to affect every day life.

The understanding of genetics and DNA paved the way for new technologies in biology and medicine, and the explosive ownership of TV and cars, as well as cheap plane travel, greatly reduced the apparent size of the world.

The politics of this period is interesting, with lots of opportunities provided by the Cold War.

If TL 6 was about bigger, faster, cheaper compared to previous periods, then TL 8 was all about smaller, faster and more disposable. Just as computers moved from being the province of large universities to being household items, so telephones moved from household items to personal devices carried by everyone.

TL 8 covers the period from around 1980 to around 2020. Of course, this is based on a European/American view of things.