I think this is pretty much the best external resource extraction system for GM. It has a progress bar to show how the resources are being extracted. Or you can have the game play itself be happening while loading resources. All other loading systems I've seen tend to freeze the game while they load the resources since you can't create multiple threads in GM. If you don't know what that means, never mind...
This extracts from 7zip files, so you can have password protection and keep your resources secure. To make your own archives you can just use the 7zip program.
www.7-zip.org
Here's kow's words from the manual. I think these were also his words from the original topic.
Gm currently has no way of Loading external files directly from inside an archive (like zip files or 7z). files must be extracted - then loaded - then deleted.
this system was designed to manage all that for you while keeping your resources safe! in fact it takes the whole loading concept to the next step by helping you create interactive loading screens like a pro console game, thus keeping your players glued to the screen while you manage your resources. it also includes a set of scripts to help you create archives in REALTIME on the fly without interrupting gameplay! so now you can save your games or highscores and not worry about anyone modifying them! works amazing for netplay too! imagine sharing multiplayer maps! just archive the resources and send away!
im sure many of you have played console games that have Loading screens when you go from one level to the next. Many times, these games will have neat animations or even interactions like super simple mini games. REAL allow you to create such interactive Loading rooms. It includes its own Loading bar (fully customizable and easy to replace with your own), support for tons of archive formats, is the most secure during its extraction and load, and best of all .. its REAL easy to use. =)
[ -Features- ]:
* allows you to import sprites/backgrounds/sounds and even use it as a regular file extractor.
* Support for loading SXMS audio. ( requires some uncommented lines in Load_Step script) supports SXMS 3 as well as 2
* Loading progress bar with 2 modes of messages. display file loading / display percent loaded. (easily replacable)
* can run from anywhere as well as extract TO anywhere or archive anything as long as DLL and EXE are together.
* secure archiving of files --uses top of the line file and password encryptions.
* supports the following formats:
o 7z
o ZIP
o GZIP
o TAR
o BZIP2
o RAR (only browsing and decompression)
o CAB (only browsing and decompression)
o ARJ (only browsing and decompression)
o Z (only browsing and decompression)
o CPIO (only browsing and decompression)
o RPM (only browsing and decompression)
o DEB (only browsing and decompression)
o LZH (only browsing and decompression)
o SPLIT (only browsing and decompression)
o CHM (only browsing and decompression)
* scripts return index values like the _add functions in the manual (note: for sound it can only obtain these AFTER the files are physicaly loaded.)
* Realtime, you can have animations, movies, simple gameplay happening while stuff loads!
* allows you to Store your external files into archives!
o supports
+ 7z
+ zip
+ gzip
+ bzip2
+ Z
+ tar
* Always welcoming suggestions for improvement.
He also said to give credit to these people if you use this in our games...
Credits
kow
porfirio
kickboxer89
battlegorge.
potnop(if you use my upgrade)
Trouble Shooting
Problem: This isn't working at all, I keep getting errors:
Solution You most likely downloaded my 5.1 update but didn't download version 4 as well. Download either Real Loading 4 Core or Real Loading 4. This includes all documentation and required files, while 5.1 is only the Game Maker file that contains internal code to use the system.
I might also upload my way of extracting with REAL, because I know this seems complicated and you guys want a good example. The one that comes with REAL Loading is also a bit complicated. My way of using REAL is more efficient I think and simpler to understand. I might upload that some time...
Real Loading 4 Core
Here's the original REAL loading core made by kow. It has all the required stuff like the dlls and executable files and a manual. You need this. If you want my little upgrade download the 5.1 file below also. This is a light download without the sample stuff included.

Mirror:
Real Loading Core 4
Real Loading 4
This also has all required files but it also includes a sample file and archive. If you never used REAL you might want this to have a better idea of how to work with REAL.

Real Loading 5.1b (Mostly a patch, you need the other files)
Here's the editable core file with scripts modified by me. It makes it so the engine only extracts needed files instead of the whole archive. Just use it as you normally would but replace all your REAL scripts with mine. I think you only need a couple but just to be safe replace em all since I'm not sure exactly each modified script. You need to download Real Loading 4 or Real Loading 4 Core for all the other required files including the manual. BTW, this is an upgrade over my original upgrade so if you had this before you need this one. It solves a pretty major problem with the old one. The old one didn't do what it said it would.
Also all the code that kow wrote, I reformatted so it's a lot more readable. For me it's so much better on the eyes because now I can understand what all the code does. I decided not to add all the semicolons where they need to be in case I mess something up. If there are problems someone tell me because I might have messed something up just by reformatting the code. I tested it in my game and it all still worked but you never know.
Also when creating archives with 7zip or any other program be sure the "create a solid archive" option is set to off if using 5.1b. Extracting a solid archive requires that the whole archive be extracted. I think it's fine if you have this option on for the original versions since those actually extract the whole archive.
ATTENTION!! This game maker file simply contains code that I modified. For the system to actually work you need to download either Real Loading 4 or Real Loading 4 Core and use the files that come with it. The needed files are "7za.exe" and "run.dll"
Oh and one more thing before you download this file, read the above attention statement if you haven't already!!!

Mirror:
Real Loading Core 5.1b -my little update
Edited by Potnop, 18 June 2008 - 03:24 AM.