TL;DR: There is no information on the history of the program pre-Ender's time in any of the books (I read 100% of them except the very last not-yet-released one). We have an idea of why it took Ender somewhere, but not why that specific setting.
The only real "technological" insight into how the game was designed came from "Shadow of the Giant", between Graff and Bean:
"The game was created for a very specific purpose. Pattern finding in databases wasn't—"
"Oh, come on," said Bean. "That's all it did. Patterns in our behavior. Just because it assembled the database of our actions on the fly doesn't change the nature of what it was doing. Checking our behavior against the behavior of earlier children. Against our own normal behavior. Seeing just how crazy your educational program was making us."
"I'll see about turning the mind game into a financial manager. The program is a complex one. It does a lot of self-programming and self-alteration. So maybe if we ask it to, it can rewrite its own code in order to become whatever you want it to be. It is magic, after all. This computer stuff."
"Ender's Shadow" has some high level info as far as what the game's purpose is:
"There's a diagnostic / therapeutic game that all the children play -- he hasn't even signed on yet."
"He'll know that the game is psychological, and he won't play it until he knows what it will cost him." (Graff and Sister Carlotta)
"He knows it isn't a game. He doesn't want us analyzing the workings of his mind." (Graff)
"Stop hiding for one second, can't you?" snapped Dimak. "You know perfectly well that we use the game to analyze personality, and that's why you refuse to play." (Dimak to Bean).
"Sir, the whole purpose of the program, the way it works, is that the computer makes connections we would never think of, and gets responses we weren't looking for. It's not actually under our control."
"We don't use the word 'intelligence' with software. We regard that as a naive idea. We say that it's 'complex.' Which means that we don't always understand what it's doing. We don't always get conclusive information." (Major Imbu)
"Ender's Game" goes into more details: (Major Imbu reporting to Graff)
"Colonel Graff, I wasn't there when it was programmed. All I know is that the computer's never taken anyone to this place before. Fairyland was strange enough, but this isn't Fairyland anymore. It's beyond the End of the World, and--"
"I know the names of the places, I just don't know what they mean."
"Fairyland was programmed in. It's mentioned in a few other places. But nothing talks about the End of the World. We don't have any experience with it."
"And the mind game is designed to help shape them, help them find worlds they can be comfortable in."
"The End of the World in the game isn't necessarily the end of humanity in the bugger wars. It has a private meaning to Ender."
"You've been isolating the boy. Maybe he's wishing for the end of this world, the Battle School. Or maybe it's about the end of the world he grew up with as a little boy, his home, coming here. Or maybe it's his way of coping with having broken up so many other kids here. Ender's a sensitive kid, you know, and he's done some pretty bad things to people's bodies, he might be wishing for the end of that world."
"Or none of the above."
"The mind game is a relationship between the child and the computer. Together they create stories. The stories are true, in the sense that they reflect the reality of the child's life. That's all I know."
(discussing getting a picture or Peter from non-IF network without requisition authorization) "Not just every day. Only when it's for the child's own good."
"OK, it's for his good. But why? ..."
"Honestly, sir. I don't know. And the mind game program is designed so that it can't tell us. It may not know itself, actually. This is uncharted territory."
"You mean the computer's making this up as it goes along?"
"You might put it that way."