/vr/ - Retro Games

I've got a dumb question. How did id know to make warm-up levels at the start of an episode? Did they talk about it? Was it intuition, insight from previous games, ancient vidya discussions, maybe D&D experience?
The general impression I get from older PC games is that they are hostile and inscrutable. I'm thinking back to System Shock, Ultima Underworld, Daggerfall, and they all start with an expansive level/dungeon, comparable in size to any other in the game.