Portal: Prelude, as its name implies, is an unofficial prequel to the game Portal. Its story revolves around the pre-GlaDOS epoch way before she was plugged in. Back then, test subjects were still monitored by real Aperture Science employees, a tedious, dull, and repetitive job. One of the reasons why they decided to build a great artificial intelligence that could both replace them for these complex tasks and also take responsibility for many other functions within the complex while competing with Black Mesa's superiority. All employees of the Aperture Science complex are now eagerly awaiting GlaDOS. A little too eagerly maybe, as the unfolding events will tell... This game is totally free. It offers a bit more gameplay hours than the original Portal, with 8 chapters, 19 test chambers, 48 challenges, 6 advanced maps, a brand new storyline and more than 400 lines of English dialogue with dozens of subtitles languages.
I really can't believe that we actually had a prequel before Portal 2. I didn't even though that Portal 2 was as great as it was (I mistakenly thought it was COOP only which turned out false). This mod did a pretty good job at tiding people over. It was harder than Portal 1 and 2 combined. Particularly tests 15, 17 and 18 that I took me awhile to even solve (15 and 18 had a obscure way to get the energy balls dispensed and 17 was just to boring). Some where a little to finicky, like doing a trick shot while doing a infinite loop on more than one occasion. But it does some important things very well, first off it gets progressively more difficult without feeling like its convoluted (17 was the exception, great in theory ie inventive but boring). Great idea to use the synthetic voices to, eventhough it looks weird on real people towards the end. Its story is pretty good, not great but better than anything I could have come up with. And a nice homage.
I think that it did well with what we had to work with, and remains to me perhaps the best Portal Mod and a nice companion to Portal 2.