When Erik Wolpaw and Chet Faliszek first sat down to write Portal 2, they went mad. It certainly appears that way now, when the final version of Portal 2 that shipped in 2011 was such a resounding success, especially for a highly anticipated sequel. The first iteration Wolpaw and Faliszek envisioned got rid of three important mechanics in the Portal universe: Chell, GLaDOS and, as we knew and are still reeling over, portals. In a talk at GDC, Wolpaw and Faliszek explained why they thought that was a good idea, and how they learned it was pretty much the dumbest thing ever.

The original Portal 2 had three new things in place of the classic ideas: F-stop (the new portal mechanic), Cave Johnson (antagonist replacement) and Betty (GLaDOS substitute). Betty was a knee-high personality sphere on wheels, a piece of concept art showed, and she spoke in quick legalese, "like those ads for medicine where they show puppies while they talk about the rectal bleeding you're going to have," Wolpaw said.

Portal 2 took place in an earlier, happier Aperture, with Cave Johnson as a pivotal, eccentric Southern billionaire, rather than the millionaire background character he became in the final version. They played an early demo video of this Portal 2 world, which had transforming environments -- a sunny, sandy beach and cabana quickly transformed into a sterile test chamber.

Valve playtested this Aperture and found players were dismayed by the lack of portals -- it's the name of the game, guys -- and so Erik and Faliszek added GLaDOS and portals back in. They then tried a run with a new playable character, a blonde, not-Chell human whom GLaDOS didn't recognize. Playtesters were disgusted and insulted by the impersonal meeting, and Valve added Chell back in.

Wolpaw and Faliszek played around with Wheatley, at one point killing him for good in the first half, and they had multiple "fake" endings scattered throughout Aperture, one of which became the real ending in the final game.

We're just glad that eventually, Wolpaw, Faliszek and the entire Valve team finally realized that there was just no way to make Portal 2 without thinking with portals.

This article was originally published on Joystiq.