Leaked Portal Prequel F-stop Recreated as a Playable Game

WHO:

Engadget - Valve developed the canceled Portal prequel F-Stop.

The Verge - Leakers assembled a playable version of F-Stop; some of its dialogue and elements later appeared in Portal 2.

TechPowerUp - Fans rebuilt Valve’s scrapped Portal prequel, “F-Stop,” using material from three separate leaks.

The Verge - Valve divided into five teams to work on video game experiments during the “Directed Design Experiments.”

WHAT:

Engadget - Leaked material was compiled into a rough, playable version of F-Stop, described as the closest thing to a release likely to be available.

The Verge - The rebuilt game is nearly complete, and videos show its full campaign.

The Verge - F-Stop differs from the main Portal games: its camera mechanic lets players capture an item by photographing it, then place it elsewhere using Polaroid-like photos.

TechPowerUp - The rebuild drew on three separate leaks.

WHERE:

The Verge - The final pieces needed to assemble the game were reportedly posted to the Valve Cut Content Discord.

WHEN:

The Verge - A 12-terabyte leak supplied most of the assets; it did not include the source code or map data.

The Verge - F-Stop was developed during a three-month period in 2007 called the “Directed Design Experiments.”

The Verge - Videos of the full campaign each run for less than an hour.

WHY:

The Verge - The source code and map data reportedly enabled leakers to piece together a nearly complete version after those materials became available.

HOW:

The Verge - Leakers combined assets from the 12-terabyte leak with source code and map data reportedly shared separately.

The Verge - The game’s core mechanic uses a camera to photograph and capture objects, then place them elsewhere through the resulting Polaroid-like images.

TechPowerUp - A commenter said the rebuilders were not charging money for the game and speculated that Valve might allow it to remain available.

(UPDATED November 2, 2026 09:58 UTC)

Fans have rebuilt Valve’s canceled Portal prequel, F-Stop, into a nearly complete playable game. The reconstruction combines material from three leaks, including source code and map data. Unlike Portal, F-Stop uses a camera to capture objects and place them elsewhere.