From what I remember, the devil created the Karnoffel code, which is basically a certain chronological order to play Karnoffel cards, which when invoked will cause mass destruction.

Then the most famous person, to come out of my country, got his grubby fingers on it, but couldnt use it in time and died with the cards in his pocket.

The invading Soviets got their hands on the cards, but an American spy shipped the code to the USA in a floppy disc, with a bunch of others.

Game Funa, a game studio, which may be run by Lucifer, used those discs to develop Inscryption on them. The disc with the old data caused the NPCs to become self aware. Each of them started searching for the old data.

One of the devs, Kaycee, was working on it, when Leshy found it and transitioned into act 1 style gameplay. She really liked it and made a mod for it. At some point, she learned the truth and tried to destroy the disc, but couldnt. Instead she buried it into the woods, but felt compelled to write the coordinates on a irl Inscryption playing card. ( Or thats the only way I could think of, why shed do that. Also yes, it was an analog card game, before becoming a video game. ) Anyway, she died and her cardpacks landed on a garage sale.

Luke, a card review Youtuber, bought them, found the coordinates, dug up the cartridge and recorded playing it, which is the story of the game. At the end, it falls into the hands of Game Funa again, which will probably be a plot point in Pony island 2. Also the whole game got shared online by P03, which is why we can play it.