GDC: A Portal Postmortem

GDC: A Portal Postmortem

Kim Swift and Erik Wolpaw reveal how they wrapped narrative into the design of Portal.

One of the last sessions at GDC 2008 — completely packed — was a postmortem on Valve’s Portal that delved into how the team wove narrative into the game. Level designer Kim Swift and writer Erik Wolpaw say their success is due to insane amounts of play-testing and development constraints (namely a small team and equally small budget).

GlaDOS.
If the Portal team had had a lot of resources, GladDos would have ended up a roving robot companion instead of a disembodied voice, says Wolpaw. But, as it turned out, it was a perfect solution to the narrative in Portal.

Companion Cube
The team was designing the "box marathon" level that required the player to transport a box throughout an entire map. The only problem was, says Swift, is players didn’t get it. They’d forget to take the box with them, or leave it behind after completing a puzzle. "Players weren’t getting attached to the box," says Swift.

Luckily, Wolpaw was reading some declassified government interrogation documents and learned that isolation leads subjects to become attached to inanimate objects. "You’re alone the whole time, so maybe if GlaDOS needles you a few times…," says Wolpaw. "After we put in dialogue, no one forgot it any more."

Play-testing
"Play-testing is probably the most important things we ever did on Portal," recounts Swift. "Actually sit down and watch people play your game." Watching how they react tells you what they want from the game, where they need more training, where you need to reinforce gameplay mechanics, and whether they get the story.

Story
Wolpaw has a philosophy: games have a story-story and a gameplay story. The two shouldn’t contradict each other. His example was Clive Barker’s Undying. On the one hand, you have this house full of monsters who are trying to kill everyone within, and on the other the player goes around inquiring into non-player character health instead of warning them of their impending doom. There’s a disconnect. So with Portal, he set out to never let the two stories contradict each other.

One of the more powerful elements — the insane scrawls scattered throughout the testing facility — were a direct result of not having the budget to create the fellow test subject the team had planned on introducing later in the game. Instead of cutting back story, they decided to manifest him in these rooms. It made for a lean story-telling experience.

"Without the constraints, Portal would not be as good a game," says Erik Wolpaw. "Embrace constraints to fuel creativity."