Portal: Prelude, as its name states it, is an unofficial prequel to the game Portal. Its story revolves around the pre-GlaDOS epoch, even before she was plugged in. At this time, test subjects were monitored by real Aperture Science employees, whose work was tedious, lengthy and repetitive. This is why they decided to build a great artificial intelligence that could both replace them in these difficult tasks, and also take responsibility for many other tasks within the complex and compete with Black Mesa's superiority. All employees of the Aperture Science complex are now eagerly awaiting GlaDOS. Maybe even a little too eagerly, as the upcoming 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 speech with dozens of subtitles translations.
All the files needed to make Portal: Prelude run. This version is exactly the same than the "installer" version except that it works better for Mac OS since it's a simple zip file. Valve ported their Source Engine under Mac OS without telling anyone and especially not me. Now I don't have the time, motivation and knowledge to port the game to Mac myself, but I can provide you with a zipped version and instructions on how to make it work. It's a bit tricky but so far it worked when we tested it on a Macbook. Instructions on how to make it work are available when you click here:
Extract to sourcemods folder. Open gameinfo.txt inside the Portalprelude folder. Underneath Filesystem there should be a section called FileSystem:
replace it with this:
WHY PORTAL: PRELUDE DON'T RUN ON MAC OS
I've been investigating with a mac-user friend for 4 hours what could be going wrong with Portal on Mac OS to prevent Portal: Prelude from running and the news are half bad and half good.
The bad news is that Valve lied to us (again) when they said the Mac version of Portal was a "native versions rather than emulation" and that "PC and Mac build at the same time, automatically, so the two platforms are perfectly in lock-step" [source]. The Mac version is very different than the PC version in the way that it partially drops the support for third party mods. I don't know if this was intentional and if they're aware of it, but it sucks bad. If you want to express to disappointment, you should directly email Valve's CEO and tell him: gaben@valvesoftware
The good news is that it's still possible to make Portal: Prelude run under Mac OS using a few extra steps I'm going to explain.
PROCEDURE TO MAKE PORTAL: PRELUDE RUN UNDER MAC OS IN 3 STEPS
First, install Portal and Portal: Prelude. You should put Portal: Prelude content in the /Users//Documents/Steam Content/sourcemods/portal prelude folder. Watch out though, because they said this location was going to change soon. If you encounter a problem while unzipping Portal: Prelude it's because there is something wrong with the default Mac OS un-archiver. Using the unzip command-line tool works just great. I don't know what's wrong but I'll try to re-upload a version that was created under Mac OS for what it's worth.
Then problems arise. The Mac OS version seems to drop the support of the -game parameter and thus, the support of third party mods in an elegant manner. Also, it seems that it drops the support of spaces in folders, thus, "portal prelude" is not recognized anymore. What you have to do is to create a symbolic link in another location to make Portal aware that new content is available. For this, you have to open Terminal (using Finder for example) and type the following commands:
This will tell Portal that new content is available next to him but not how to use it, this is the next step.
When this is done, restart Steam and Portal: Prelude should appear in you games list. Beware though, this shortcut won't work. Basically, as they dropped the support of third party mods, you'll have to tell Portal to use Portal: Prelude content instead of having another standalone game besides it. The way to do this is weird, but works.
So far it looks like this method works at a 100%, I didn't play the whole game though but we had everything working from cutscenes, voices, subtitles, gameplay, and such. If you want to play Portal again, simply remove the -game portalprelude -dev from the launch properties.
Now on a more technical side, I'm totally unsure WHY the hell you have to launch the game in developer mode (-dev) for it to work, but we never managed to make it work without it. We are also sure there are probably ways to do this differently. We investigated a few things, like the open command of Mac OS combined with the command line options of Steam. Basically, we tried this:
It works perfectly, but only when Steam isn't already launched. Mac OS seem to catch the call and prevent it when Steam is already running. We don't know how we could bypass this. We also elaborated on the Steam Browser Protocol to make it launch Portal with Portal: Prelude content like this:
But so far, the Steam Browser Protocol doesn't seem to be able to deal with parameters, so we gave up.
If you are knowledgeable enough, maybe you'll find a more elegant solution to this problem. We hate the current solution because it forces you to switch between Portal and Portal: Prelude and you can't have both working at the same time. If you do find a more elegant solution, please post it on our forums : Portalprelude.com