Fans Rebuild Valve’s Abandoned Portal Prequel ‘F-Stop’ From Three Separate Leaks

F-Stop, the canceled 2007 Portal Valve prequel, is now playable after the community pieced it together from several leaks. Most of its assets were already in the massive 12TB Steam2 archive that leaked in August, but that backup didn’t include the game’s source code or its mapsrc data, Valve’s folder for map source files. Both of these missing items appeared on the Valve Cut Content Project’s Discord server over the past few days, where the team verified the map files before everything was merged into a single version. It’s not entirely complete, as some textures and dialogue are still missing, but YouTube playback suggests it’s largely stable and the campaign ends in less than an hour. Getting a copy yourself is another matter, since the Discord server apparently went invite-only after all the attention.

F-Stop grew out of what Gabe Newell later called Directed Design Experiments, a three-month period in which Valve split into five teams, each building their own prototype. Its central idea is an Aperture Science camera that photographs an object so you can place it elsewhere to solve puzzles, a concept that the 2023 game Viewfinder later explored. Valve staff apparently liked it, but testers were less impressed. It was shelved and some of its dialogue, characters, and mechanics were reworked in Portal 2. Playthroughs show an early Cave Johnson speaking to the player (without the voice of JK Simmons), as well as personality cores acting as puzzle companions. Valve has not commented on this project and there is no indication of an official release.