Portal: Prelude is a user made mod for Portal with a story that takes place before the events of the game Portal. It is not to be confused with the official prequel that Valve is currently working on. Go to www.portalprelude.com for more information.

"Portal: Prelude, is an unofficial prequel to the game Portal. Its story revolves around the pre-GlaDOS epoch, even before she was plugged in. At this time, test subjects were monitored by real Aperture Science employees whose work was tedious, lengthy and repetitive. This is why they decided to build a great artificial intelligence that could both replace them in these difficult tasks, but also take responsibility for many other tasks within the complex and compete with Black Mesa's superiority. All employees of the Aperture Science complex are now eagerly awaiting GlaDOS. Maybe even a little too eagerly, as the upcoming events will tell... "

Download the Portal: Prelude Mod (775 MB)