Down to the Last Save

Portal Prelude seemed it would be such an awesome mod for Portal, but this review from Irish Taxi Drive from the Something Awful forums sums it up for me:
Portal: Prelude is a mappack that takes place before the events of Portal, and attempts to explain Aperture Science pre-GLaDOS. To effectively understand how much of an [...]

So I stumbled upon a while back on a blog called Portal Prelude. Portal Prelude started out as a personal project that focuses on days before GladOS (think a unoffcial prequel).
Its story revolves around the pre-GlaDOS epoch,before she was plugged in. At this time, test subjects were monitored by real Aperture Science [...]