Kim Swift and Erik Wolpaw, two of the key developers on Portal, gave GDC attendees a behind the scenes look at The Orange Box hit, focusing on the process of integrating narrative and design. The two also showed early and, by their own admission, failed, version's of the game's final boss fight with GLaDOS, the talkative, ever present artificial intelligence. They highlighted three attempts at making a successful boss battle, driving home the fact that ample playtesting brought them to the incinerator battle they ultimately settled on.
Since Portal is essentially a first person puzzle game, the team initially thought it would simply end on what they thought was appropriate, a puzzle more complex than anything the player had seen before. That solution, they said, was a pain.
Their first proper boss fight attempt, when GLaDOS was just a translucent shimmery cube, was the "Giant Laser" battle. Players had to direct lasers back at GLaDOS to destroy it. It wasn't fun and the lasers were just too difficult to aim.
Boss battle attempt number two, their "Mortal Kombat" stab, was full of intensity. Missing flying, turrets spawning, an out of place firefight than belied Portal's slower paced, cerebral gameplay. It also sucked, according to Wolpaw.
Attempt number three was a chase sequence. But the pacing was horrible and there was no opportunity to communicate to the player.
Around this time, Wolpaw said the Half-Life 2 Episode Two guys excitedly said to the Portal team "Our final battle is gonna have 100 Striders, you're going to get to drive a car and fight dozens of mini-Striders. It's gonna be awesome! What are you guys gonna do?"
With a tiny team on Portal, they simply couldn't match a boss battle that epic, and they ultimately created the time limited incinerator set piece as the final fight.
The Portal team's limited resources also forced them to "trim the narrative fat" elsewhere. Swift talked about a proposed scene involving "The Rat Man" the fellow escaped test subject whose writing and sketches appear in the game's later levels.
As far as Portal's other co-star, the Weighted Companion Cube, it's origins lie in addressing player frustration with finishing the "box marathon" level that features the lovable crate. Wolpaw said that he was inspired to give the Cube a little personality by what he'd been reading in de-classified government interrogation manuals. "They're great," he said, pointing to findings that people in isolation become emotionally attached to inanimate objects.
Wolpaw had advice for those trying to write a "funny" game—"God help you." He related his previous experience with Psychonauts, on which he was one of the game's writers. Upon name dropping the cult favorite, Wolpaw was met with a huge round of applause. "More people just clapped than bought the game," he joked.
"Hearing macho tough guy dialogue is annoying enough, but hearing the same joke fifty times, a couple of which may actually be funny can be much worse," Wolpaw said. He called the playtesting of Psychonauts "psychological torture", his comedic script met with silence when being pumped out of 40 monitors in the QA section at Double Fine Productions.
When the two had wrapped up their session, taking questions from the audience, the discussion quickly moved to plans for Portal 2. Swift and Wolpaw mostly dodged the question, with the latter saying "I'm just trying to bask in the moment... without people bugging me about it."