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.
Despite all illogical and generally boring puzzles, all of which I've managed to complete by myself, I feel bad about this mod. It could be some good, if it had no plot and no voice dialogs. Scenario is such an idiocy. Scientists that talk like mentally retarded while killing girls in test chambers? Really? And after Abby survives they are making a party with cake and balloons? If I would be her, I'd killed every single of them with chair or other staff that comes in hand. GlaDOS killed everyone with gravity beams and lasers? Whole place got half-destroyed before Chell's arrival? I feel like devs haven't understood original Portal's plot at all.
Dialogs is another idiocy. And its not that using Microsft Sam voice and other tools is bad, it's text in these dialogs that is horrible. It sounds like a bad parody on Portal. Where in Portal have you single time heard words "****", "****", "crap"? Comment on Abby's ***? Shows decency level of creators. "Jokes", if they can call be that, are flat and too far from sparkling humor level set by the original. All other phrases makes no more sense then maps.
In addition, while some music tracks fit very well in Portal theme, choosing Chemical Brothers for final fight is another retarded idea. "GlaDOS likes it more then cake"... pffft.
Overall, I'm aware it's only a mod, but I'm judging by the goals set by this mod. If it whould be only a map-pack with puzzles, it could be good. But it tries to be something more and fails at that generally.
I agree with Darkurai's review, he explained all flaws better then me.