The same shape as the game you played, with your trade in it. A player starts making one thing by hand. They buy machines, sell the output, and get bigger. Then, near the end, the operation stops needing them — it runs itself and starts consuming everything around it. That last part is the whole point, and your job is to decide what it looks like for your trade. A bakery's sourdough starter begins making its own flour. A coral nursery's reef settles on everything in the ocean.

You don't write any code or numbers. You choose the words, what the game rewards, and a handful of decisions the player has to make. Everything else is already built.

It takes about a minute. Nothing is permanent until you say so.