The world has remained much the same for the last thousand years or more. Men are born, grow up, live, and die. Kingdoms rise and fall. Armies are gathered and obliterated against each other. Cities grow prosperous, and are sacked by jealous rivals or angry gods. Nobles launch petty campaigns of insult and intrigue on each other in the eternal dance of lineages and inheritance.
Conquerors lead crusades to half a dozen holy lands, in Firyn, in Gastonia, to the islands of Ionia, and in those crucibles a few lucky souls emerge as glorious heroes, forgetting the rivers of blood that carried them there. Cities change hands, and the pyres of the dead stain the sky black. Small villages in the middle of nowhere are claimed by new lieges in treaties half a dozen times in a century, and the only thing that changes is who they tithe their harvests to. Monsters prey on man and beast alike, until they're killed by a great hero, the end of their reign of terror immortalized in tavern songs - but another monster takes their place sooner or later.
Any real progress is hard-fought and slow, a grinding effort against the world's eternal war against itself. Pigs and potatoes spread across the world. Priestly orders dedicated to healing the sick spread their teachings, and make a small dent against the looming and inevitable specter of plague.
You're going to change all that, hopefully. Because, you see, you have something very special...
It doesn't look like much. It's a small gem that shines with a brilliant blue light at a thought, showing instructions and images of a future that might come to pass - but only to you. To everyone else, it's just a glass bauble.
It showed you the future, you think. For a moment, an entire world of detail was made bare to you, books and books worth of a strange language that you somehow understood. Either that or you've gone utterly mad. You grew dangerously sick, feverish. You were insensate and bedridden for a week or more - you're not entirely sure how long.
You saw glimpses of a forest of vast workshops, bigger than a cathedral, where metal and wood were arranged by dozens of workers. Temples to industry and craft. Buildings reaching so high in the sky it seemed absurd. Carriages that sped down roads as if propelled by magic. Strange arrangements of wire and glass that burned brighter than a thousand candles! And around all these miraculous objects, people. People acting the same as they always do: Complaining about their neighbors, making bawdy jokes, gossiping and griping and telling stories, inured to the miracles that surrounded them and they used without thought.
They were mostly happy. Not universally - you saw mothers weeping for their babies in those visions. Lovers having arguments, swindlers plying their tricks, addicts of strange drugs killing each other with weapons that slay with a flash of light and a boom of thunder. You saw an awful nightmare of mud and blood, mangled bodies strewn across ruined fields, the cathedral-workshops spitting out instruments that sang the music of death.
The good outweighed the bad in the visions, though. You can't remember specific details for most of what it showed you, but you saw so much - everyone was so rich. It was a surprise and a tragedy if children died of sickness, instead of a sad fact of life! There were huge structures holding unthinkable amounts of books, those rare and expensive tomes of learning! Even lowly day-workers and beggars wore warm coats and occasionally had a meal of meat!
You have never wanted anything as badly before. It will be supremely difficult, no doubt. Forces you don't understand will oppose you. Setbacks you never could have anticipated will beset you. You will have to deal with the skepticism of the people if you want your changes to spread. It can't only be you - you'll have to teach people to make these miracles happen by themselves.
But you're going to make that miracle world a reality even if you die trying.
(Author's note: Check out the Informational threadmarks, the ones that aren't mechanics or stats I tried to write in an entertaining-yet-informative way.)
What did your Codex Crystal show you in that first, magical moment? Even now, it turns to similar topics more easily under your will. Perhaps it's trying to help you, frustrating as it is - you can see how these relatively simple methods and machines will be easier to create in reality than the stranger things you can barely understand.
[] Numbers and words arranged in great tables. Addition and subtraction, goods moving in and out as the numbers shift and slide. Money changing hands and somehow returning larger. Great ships loading exactly the right amount of goods and supplies for their journeys.
Codex will start with trade and finance ideas.
[] A massive kiln glowing with heat. Workers pour ore in and a huge bounty of molten metal spills back out. Iron is shaped into hundreds of ordinary tools that people use to do their usual work with much more ease. There's so much precious metal that it's even used to nail wooden boards together!
Codex will start with ironworks technology.
[] Neatly-ordered fields divided along clean lines. Massive farms providing truly huge harvests. Slightly-different crops and livestock that seem more bountiful and healthy than before. Wooden contraptions process plants with surprising efficiency, and a bolt of cloth hangs off a strange machine.
Codex will start with agriculture ideas and technology.
[] A metal cylinder with strange protrusions and bars. It hisses in a slow beat, moving back and forth to pump water up a hill, power a great bellows, or even move wagons without horses. The Codex flickers agitatedly along the many steps in its construction, as if warning you that it will be a difficult project.
Codex will start with a steam power technology and will prefer unlocks that lead towards building and using it, but this is a big project.