(NOTE: I'm taking a break from campaign history to get some basic information about the world itself posted, preparatory to redesigning the site somewhat to make it more useful as a reference source. This might take months, but should make a lot more sense when it's finished. Or it might be finished soon. In any case, I do intend to finish the campaign history, at least in overview, as the opportunity arises.)
The world of the Black Steel campaign has been made as much as possible like our own, apart from a few key differences with wide-reaching consequences. The design of the world, from the laws of physics to the diversity of the plant and animal population is intended to balance three main goals:
1. Familiarity: Most of the time, characters in the game should be able to behave as though they lived in a normal medieval earth society, without trying to work out (for instance) the physical requirements and consequences of a world where gunpowder wouldn't burn, the social consequences of one that lacks horses, or the tidal effects of multiple moons. As a result, the basic laws of physics, most familiar animals and plants, and important astronomical features are essentially the same in the world of Black Steel as they are on our Earth.
2. Explorability: The shape of the world's land masses, the locations of different societies and ancient ruins, and some of the animals and plants the characters can expect to encounter, are wildly different from those found on Earth. Some of these are natural consequences of each other, or of the presence of sorcerous power in the world. Others are present simply because a fantasy world whose secrets could be discovered in an almanac as easily as within the story just wouldn't be very interesting. As such, the world map is completely different from Earth's, strange races of humans and other sentient beings dwell across the world, usually in places hidden to "normal" people, and various plants and animals not familiar to us dwell in the world as well, from creatures with ties to magic to those that went extinct on ancient earth but survived in pockets in the Black Steel world to those that evolved naturally but differently than they would have here due to the differences already described.
3. Fantasy: The Black Steel world features magic, dragons, and various other hallmarks of medieval fantasy. Laws of magic allow apparent "violations" of the laws of physics within their limited scope, and fanciful or archaic animals or plants -- where they happen to appear -- fill or obviate the ecological niches that would otherwise have been used by various "normal" creatures. Balancing these facts with my goal of "familiarity" means taking various steps to limit the impact of these fantasy elements on normal people's everyday lives without putting them beyond the reach of player characters or their stories. It's a fine balance, but by no means impossible, and as long as the world is familiar in its workings in most times and places, for most humans and other creatures, it's fine for important fantasy events to be discoverable and even to have major impacts on the world's history. Occasions can arise when fantasy elements loom large in people's everyday lives, but these will be important, story-driven events, significant in their rarity.