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A New Documentary Series is Exploring Valve's Original Pitch for Portal 2

Featuring Valve's original F-Stop prototype, Exposure will show off the Portal prequel we never got.

This article first appeared on USgamer, a partner publication of VG247. Some content, such as this article, has been migrated to VG247 for posterity after USgamer's closure - but it has not been edited or further vetted by the VG247 team.

Valve's games have had their development history rigorously picked apart by fans, but one scrapped prototype has invited speculation for years on end. After Portal 2's release, Valve developers teased a puzzle mechanic named F-Stop that almost became the basis of a fully fledged prequel to Portal. This year, with Valve's permission, a team of two indie developers are finally setting out to reveal how the F-Stop mechanic worked in a new video series called Exposure.

The first installment of Exposure shows off the F-Stop mechanic in a simple Aperture Science test chamber environment. F-Stop's puzzle solving revolves around the Aperture Camera, a device that can capture objects and place them back into the environment at different scales and orientations.

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In the video, the player needs to reach a door on a raised platform, and there appear to be at least three viable solutions: making a staircase from cubes of different scales, creating a makeshift elevator by placing balloons on a cube, or capturing a ceiling fan and placing it on the floor to propel the player upwards. Our sister site Rock Paper Shotgun points out that the object scaling on display in Exposure is not too dissimilar from the perspective-based scaling in 2019's Superliminal, another first-person puzzle game.

Exposure is being made by Tristan Halcomb and Graham Dianaty of LunchHouse Software. "Exposure was a side project of ours that we started in our down time," Halcomb tells USgamer. "After a few emails back and forth, [Valve] approved us to share what we had with the community." LunchHouse is also developing Punt, a Portal-inspired puzzle game, with a licensed branch of Valve's Source engine.

F-Stop was first mentioned in Geoff Keighley's Final Hours feature on Portal 2's development and teased again by writers Erik Wolpaw and Chet Faliszek at a GDC 2012 postmortem. "I'm not actually going to go into the details of the mechanic, because hopefully someday we'll use it again," said Wolpaw in 2012. Up until the debut of Exposure, everything Valve fans have gleaned about the nature of the F-Stop mechanic has come primarily from datamining. Videos of the mechanic in-action never surfaced.

Holcomb and Dianaty's current plan for Exposure is only to explore gameplay elements and mechanics that were present in Valve's original F-Stop prototype with a series of videos. "As far as length goes, there's enough mechanics at play to make over a dozen, but we'll attempt to condense it to five or six videos," says Holcomb. "We also want to discuss the future of the project a bit more with Valve to see what opportunities we may have going forward before committing to a follow up, so we're working based on their schedule to some extent." Valve did not respond to a request for comment about F-Stop and Exposure prior to publication.

Certain elements of the F-Stop prototype's setting and story didn't get completely abandoned. While it was originally set as a tale revolving around Aperture founder Cave Johnson and a robot mannequin uprising, chapters of Portal 2 were set in the ruins of Aperture's mid-century test chambers.

With Half-Life: Alyx on the horizon and another Geoff Keighley report on its lengthy development cycle to follow, it won't be long before fans have another info dump on several secretive years of Valve history to pour over. Keighley promises that The Final Hours of Half-Life: Alyx will cover everything that's happened at Valve over the last decade; perhaps alongside details on In the Valley of Gods and Valve's VR and AR experiments. We may even learn whether Valve ever did revisit F-Stop before focusing on its return to the Half-Life series.

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Portal 2

PS3, Xbox 360, PC

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Mathew Olson avatar

Mathew Olson


Mathew Olson is a writer formerly of Digg, where he blogged and reported about all things under the umbrella of internet culture (including games, of course). He lives in New York, grew up under rain clouds and the influence of numerous games studios in the Pacific Northwest, and will talk your ear off about Half-Life mods, Talking Heads or Twin Peaks if you let him.