This is a video from GDC where two of the writers from Portal 2 talk about the different ideas they had for Portal 2 and what worked and didn't. Interesting to watch. Do note that it contains spoilers for Portal and Portal 2, so if you haven't played those yet but want to, don't watch this video!
The great thing is that they actually show some footage from stuff they tried during development but which eventually got cut or was changed.
Portal 2 post mortem
Re: Portal 2 post mortem
will watch later.
playing the game with developer comments on also gives some great insights on how storyelements came to be.
playing the game with developer comments on also gives some great insights on how storyelements came to be.