The concepts see Portal star Chell changing her orange jumpsuit for a utilitarian test suit, while an Apeture Science sentry turret and GLaDOS personality sphere become the basis for two partners in co-op--a feature first hinted at by GameStop's listing.

"This is not supposed to look like a sexy Marvel superhero suit," concept arist Matt Charlesworth explains. "It's supposed to look like it was designed without any thought of making her look attractive. We don't want to make her be unattractive, but we want to balance that out. Chell is a test subject, so she should look like one."

Portal 2 was announced earlier this month following a cryptic ARG and a teasing change to Portal's ending. Valve has hired a student team from DigiPen--the college where students created Portal's inspiration, Narbacular Drop--seemingly to work on the game, apparently drawing inspiration from their project Tag: The Power of Paint.

The first-person puzzler sequel is due on PC, Mac and Xbox 360 this holiday season.