Portal Prelude

Portal Prelude is an unofficial mod, and as the name suggests, is a prelude to the popular Valve game Portal. This, however, is not just a mappack; it is an entire new game. A brief summary of the plot is that the game centers around a pre-GlaDOS era at Aperture Science where the testing was done by actual employees. This work was very tedious which is why they created GlaDOS--to make the job...

Portal Prelude