Did this require a saved game? Somewhere I read that the telescope code wasn’t generated until it was first revealed, and therefore that this shortcut should in fact be impossible.
No, this run must be done from a New Game. The telescope code is generated on New Game, as are all the other codes (however, the prison code only works once you've captured Gehn). The impossible ending speedrun requires you to get extremely lucky on guessing the code, which basically means doing attempts until the code is one of the ones you check first.
Did this require a saved game? Somewhere I read that the telescope code wasn’t generated until it was first revealed, and therefore that this shortcut should in fact be impossible.
No, this run must be done from a New Game. The telescope code is generated on New Game, as are all the other codes (however, the prison code only works once you've captured Gehn).
The impossible ending speedrun requires you to get extremely lucky on guessing the code, which basically means doing attempts until the code is one of the ones you check first.