That's apparently how much content there is in Portal:
As far as Portal, doing lot of speedruns, practicing various different Ninja moves, and countless maps over 3 years. Portal is my all time favorite game.
I wonder if Portal 2 will match it?
(From this thread on Borderlands. I've just finished my first pass through Borderlands - so 'finished' it from a narrative point of view, excluding the DLC. Of course, there's plenty of game left and many great weapon drops to find).