Looking for a reason to keep Portal installed on your computer a bit longer. Let me help you with that - download Portal: Prelude now. Oh, and if you already uninstalled - start that Steam download. Portal: Prelude is a fan made mod expansion which tells the story of the Aperture Science test complex before the introduction of the GlaDOS AI. The pre-release preview over at Mod DB provides a great read while waiting for the awful File Planet servers to do that thing they do. My download however, has just finished and is installing so, I'm going to play now.