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.
This review may contain spoilers
It must be admitted that if you take nothing else from this mod, its sheer scale is quite exceptional. With new characters, voicework, puzzles and approximately double the length of the original portal (not to mention its difficulty in places) it is hard to den the dedication and hard work that has gone into this mod.
The storyline is fairly solid – although I expected the malice of on of the observers to continue – which is impressive and a testament to what can happen if a mod team sit down with a plot in mind. The plot in Prelude is simple enough, you are one of the first few test subjects at Aperture Science, and are set upon to complete the chambers in order to finally see the first run of the new GLaDOS system.
The test chambers themselves are not exceptional in terms of visual but what they do provide is an extension to the game play once you have completed the original game, the storyline ties in quite well as so as a prelude it seems to fit almost to the point where can feel Valve’s wicked sense of humour creeping through.
The puzzles themselves lead you through in much the same way as the original, giving you all the instruction you need in order to succeed in some of the trickier chambers to follow.
As you progress you will find that the difficulty ramps up rather quickly and far surpasses the original game, this is perfect for those who have just (disappointedly) finished the too-short 3 hours of portal and now want more and harder.