Valve's Scrapped Portal Prequel F-Stop Is Finally Playable After 19 Years

If you've been following Valve news this past year, you may recall the 12TB Steam Leak that occurred in August. When that leak happened, it revealed the existence of a scrapped "F-Stop" project intended as a prequel to Portal, that was supposed to drop before Portal 2's development. Since then, the remaining files needed to compile a playable build have been supplied to the community-run Valve Cut Content Team.

Those who watched the Portal 2: The Final Hours dev documentary may also remember some discussion of F-Stop as early concepts for Portal 2. Indeed, traces of dialogue and lore did make their way from F-Stop to Portal 2, sometimes completely unaltered.

Aperture Science CEO Cave Johnson, voiced by J.K. Simmons, is introduced as a character in F-Stop after being teased in the original Portal. Originally, he was intended as the antagonist of F-Stop, but Portal 2's setting in the distant future forced Valve to alter those plans.

Even so, the character of Cave Johnson and the ideal of an 80s-era Aperture Science (and by extension, a peek at the 80s-era Half-Life universe) made a fairly strong impression on players, so it's easy to see why these aspects carried over.


For those who aren't familiar with F-Stop, is is a Portal prequel, but there is no Portal gun. The gameplay still features quantum entanglement (what Einstein called "spooky action at a distance,") but utilized instead with a camera. These early gameplay concepts greatly predate indie darlings Viewfinder and Superliminal, but the resemblance is undeniable.



Unfortunately, the final playable build of F-Stop is only about an hour long, and Valve developers at the time never expanded the idea to a full game. Even the similar modern indie examples mentioned, like Superliminal and Viewfinder, are relatively short experiences that can turn off players who aren't intrigued by their novel mechanics and perspective trickery.


But if you want a full look at F-Stop, YouTuber Meme Man has kindly uploaded a video playthrough of the full campaign, which we've embedded above. I wasn't able to find a playable build for myself at time of writing, but The Cutting Room Floor has a detailed page on everything we know about F-Stop so far.