"Here's kind of a golden rule of level design: finish the first level last. Then you've learned everything about the game's level design, and you're going to put it all in the first level where you want people to get excited anyway," he begins.
John Romero is a co-founder of id Software and designer on Doom. In this video, presented by Double Fine, he sits down to play the game and discuss its creation.
The resulting footage is amazing.
It's like a crash course in design and how to put together an interesting level. I won't repeat any of the lessons or anecdotes here — the video is worth watching in its entirety — but I guarantee you'll learn something, including the importance of the horseshoe shape in early id Software games.
This is one of the most influential minds in gaming discussing the creation of the one of the most influential games. Enjoy!