A Portal prequel has been brought back to life nearly 20 years after Valve canceled it, thanks to fans who pieced together a playable version using leaked files.
Known as F-Stop, the game was originally developed in 2007 and set before the first Portal. Although Valve ultimately moved forward with Portal 2 instead, a series of leaks has now given players a chance to see what could have been.
Fans make canceled Portal prequel playable using leaked files
According to Kotaku, members of the Valve Cut Content Discord community (which is currently invite-only) have managed to reconstruct F-Stop using a collection of leaked assets, source code, and map data.
The first pieces surfaced in August 2026, when a massive leak of approximately 12TB of Steam data exposed material from several Valve games, including early versions of Portal 2 and Left 4 Dead.
Following that, additional source code and map data reportedly appeared through the Valve Cut Content Discord server more recently, allowing fans to assemble a playable build.
Unlike Portal, F-Stop doesn’t involve creating portals to navigate environments. Instead, players use a camera to photograph objects before placing them elsewhere in the world to solve puzzles.
As reported by Engadget, the reconstructed version is still unfinished, with missing textures and dialogue. However, much of the campaign is playable, and footage showing the game in action has begun appearing on YouTube.
F-Stop dates back to Valve’s Directed Design Experiments in 2007, an initiative that saw developers split into teams to experiment with different gameplay concepts.
Valve ultimately opted to make Portal 2 instead, which was released in 2011.
I’m Abhishek Sharma, an author at TigerJek.com. I enjoy exploring games, testing different strategies, and turning what I learn into clear, useful guides. My goal is to help players understand the game better and improve without the usual confusion.
