It was inspired by the anime Code Geass, but bears few actual similarities to it: There are mecha called Knightmares, Geass, a couple of countries called Britannia and the Chinese Federation, a facsimile of sakuradite, and that's about it. The earliest actual POD is in the Stone Age (the appearance of Geass), which would seem to suggest that the timeline should look nothing like actual history. Nope! The world of Dichotomy is intentionally designed to look both familiar and strange, written more for the story than for the timeline itself, though oshron personally states that he's writing it as the backdrop for an action-based RPG of the same name at his own message board, Rplegacy. The other primary reason that Dichotomy isn't as radically different from actual history as it could be is for the ease of understanding by non-alternate history fans, in order for them to get much more into the story (again, in a similar vein to Code Geass).
As Dichotomy essentially covers all of human history and then some (stretching forward to the mid-21st century at most), its setting is enormous. The earliest POD is in the Stone Age, but significant changes don't come up until the Middle Ages. Thus far, the first POD leading to immediate changes are that William of Normandy's invasion in 1066 is beaten back, leading to Harold Godwinson and his descendants ruling “Anglia” for three hundred years, with numerous alternate equivalents to historical British kings until the Tudor Era (internally justified by the Tudors being Welsh) when historical figures take up the throne of Britannia (because Welsh Catholics like the Tudors called Britain “Britannia” IOTL and the name sticks after a longer Tudor dynasty). Elizabeth I has a son named Henry, who overseas the first successful colonization of North America at “Tudorstown.” At around this same time, Spain has conquered the Aztec Triple Alliance, but failed to break them, leading to persistent native resistance movements through to the 19th century. From here, the history of Dichotomy becomes more and more divergent from OTL. By the present-day, in 2032, Spain has retained control of most of South America (except for an independent Brazil), the United States of North America has acquired almost everything north of OTL's US-Mexico border as well as the Philippines, there is an independent Aztec Empire aligned to the US, the USSR and a unified Germany never came to be, and there is a persisting Napoleonic France, Austria-Hungary, Poland-Lithuania, a revitalized Mughal Empire, a more influential Arab League, and the League of Nations being a more significant entity than IOTL.
There are also numerous other independent countries, such as the Haitian Empire, Switzerland, Liberia, Uruguay, and Vietnam, as well as a number of League of Nations mandates and various protectorates of world powers, though most of the world is under administration of various colonial states.
Covering almost all of human history means that there are a lot of characters to be included ITTL. Most are historical characters while others are alternate versions of real ones to suit a purpose. Among Dichotomy's historical characters are:
Dichotomy also includes many fictional characters, many of whom occupy the roles of historical figures with some changes to their personal histories, such as: