F-Stop (or Aperture Camera), the long-rumored and unreleased prequel that Valve Corp. intended for Portal, has finally gone public — with Valve’s permission. This video, from LunchHouse Software, shows F-Stop’s gameplay and concept — basically, taking pictures of things allows you to duplicate and place them in order to solve environmental puzzles.

F-Stop began life after Portal launched with The Orange Box in 2007. The game does not involve Portal’s familiar portal gun or teleporting technology. Instead, it expands on Aperture Science’s namesake; it appears an earlier device that researchers there developed involves a seemingly magical camera.

For example, by taking a picture of a ceiling fan, and then placing the fan on the floor, the player is able to boost themselves to a higher platform and escape the test room. Players are able to resize whatever they are duplicating, too, creating a staircase out of a set of blocks for example. Attaching balloons to an object levitates it out of the room.

LunchHouse is showing F-Stop in a series of videos that the developers call Exposure. It’s not really clear what the studio is doing with the source code — which the developers say they obtained with Valve’s permission. For now it simply appears to be a documentary work, not a teaser for some other game set in the Portal canon.