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.
In the first few minutes I had with Portal: Prelude, I was very interested and somewhat curious. The voice acting wasn't that good. It didn't sound like a human, it sounded robotic and it gave me the impression the people who were talking were robots. The sign textures were low quality but the rest were fine. The gameplay was good. The test chambers were a refreshing new set of tests I really enjoyed. It was interesting yet cool that you started with the an orange portal gun and not the blue one. The tests were fun and the story was really cool and interesting. All I can say is that this is a must play mod for anybody who owns Portal.