In 2008, Portal 2 wasn’t what it is now. Valve’s sequel was originally a prequel and for five months the game had no Chell, no GlaDOS and perhaps most amazing of all… Portals.

The information comes to light in a very cool multimedia app produced by gaming journo Geoff Keighley called ” The Final Hours of Portal 2“. Keighley had an unprecedented amount of close quarter access to Valve’s work space during the development process of Portal 2 and this app is a sort of evolutionary narrative on what Portal 2 was and what it eventually became. The app includes a number of interesting details, as well as exclusive development screens never seen before. The screen above is just one example.

The game was actually going to be set in the 1950′s and was going to be based on a super secretive internal gameplay mechanic prototype called F-Stop. Valve loved F-Stop, test players didn’t. Not only does F-Stop not appear in the final game, but we still don’t know what it is. Valve asked Keighley not to tell us what F-Stop is, only reference it. F-Stop is a mystery to everyone bar Valve and Keighley.

Below is a link to the app. It’s not free but for a very in-expensive look at all things Portal 2, it’s a great read. Be warned, it does include a few spoilers but at over 15,000 words with exclusive images, videos and never before seen screens, it’s a worthy purchase.

Thanks to Kotaku

The Final Hours of Portal 2 [iTunes]