August 1, 2011 was an important day in the history of open source software. That's when Wikia finally open-sourced the ArmchairGM codebase. You can browse the ArmchairGM codebase or even grab a copy of the ArmchairGM codebase, if you feel like it!
A bit of history
Over a year ago I tried open-sourcing the ArmchairGM codebase, but my idea was met with resistance and travelling to another country just to perform code cleanup — something you can do "online" by grabbing a copy of the codebase and then cleaning it up locally — was just not possible for me.
Later on, Sean Colombo, an awesome open source developer and the founder of LyricWiki, joined Wikia's technical team since LyricWiki moved to Wikia. On July 14th, I decided to e-mail Sean, just for the sake of it, to see if he'd be willing to help me out in making ArmchairGM's codebase open source.
You can believe that I was very surprised when I didn't receive the standard "sorry, can't do" reply that I've gotten used to getting from Wikia in response to my queries, but rather a sincere reply in which Sean stated that he'd be willing to help me out. Over the next two weeks, Sean worked hard to make sure that the ArmchairGM codebase would be ready to be released by removing private passwords and such things. And then, on August 1, it finally happened.
I was amazed that he took my original request — I had asked for a few ArmchairGM extensions and the skin — a couple steps further and open-sourced the entire codebase!
About the ArmchairGM codebase
The ArmchairGM codebase is based on MediaWiki 1.10alpha; the work on MediaWiki 1.10 started on 8 January 2007.
The current development version of MediaWiki is 1.19, the latest stable version is 1.17 and 1.18 will be released soon. So, as you can see, it's a bit old. After all, ArmchairGM was running on that 1.10alpha until early 2011, when it was upgraded to use the standard Wikia codebase.
Most of the interesting things can be found on the extensions and skins directories.
The extensions directory and its wikia subdirectory contain all the extensions used by ArmchairGM and/or created by Wikia developers — including ones that were short-lived, such as Challenge, or never enabled on ArmchairGM, such as LookupContribs.
The skins directory contains all the skins ever developed by the ArmchairGM staff, including the Sports skin used on ArmchairGM from 2007 to early 2011, its earlier incarnation, called simply ArmchairGM, the Halopedia skin and the Gamespot version of it, and plenty more. It should be noted that while this directory has plenty of PHP and CSS files (and even some JS files), most of the images used by custom skins are not there — some are accessible on Wikia's servers if you know where to look for them, some are permanently gone.
What about core hacks? Wikia has done and continues to do core hacks whenever they need to do something that MediaWiki doesn't support out-of-the-box. So far I've come across a few, relatively minor, yet unmarked core code hacks in the ArmchairGM codebase.
Needless to say that such a thing will be quite difficult to do, because "1.10alpha" can mean pretty much any version of MediaWiki between r18957 (committed on 8 January 2011) and r21732 (committed on 1 May 2007) — that's 2775 revisions of code, and the ArmchairGM codebase could've been forked from any of those revisions.
Update on 15 August 2011: I had totally forgotten about the existence of the RELEASE-NOTES file. Comparing the RELEASE-NOTES file of the ArmchairGM codebase to the RELEASE-NOTES of MediaWiki 1.10alpha at various points of development allowed me to track down the revision of MediaWiki that the ArmchairGM codebase is in. I believe that it's either r20138 or a revision very close to it.
To generate a patch file showing the differences between the standard MediaWiki codebase and the ArmchairGM codebase, first export a copy of MediaWiki at r20138:
svn export -r 20138 http://svn.wikimedia.org/svnroot/mediawiki/trunk/phase3 MW-r20138
Then export a copy of the ArmchairGM codebase:
svn export https://svn.wikia-code.com/wikia/branches/wikia-ny/trunk NYC
And finally generate the patch:
diff -ur MW-r20138 NYC > diff-between-NYC-and-vanilla-MW-r20138.patch
Some changes are useless, like the change to includes/AjaxDispatcher.php, some are plain weird (like the various API changes to the files in the includes/api directory), and some changes (mostly the ones to OutputPage.php and SpecialPreferences.php) are a bit hard to read — but hey, there you have it, a file showing what changes were done to the core MediaWiki software by ArmchairGM's developers.
Most of the custom functionality that you once saw in ArmchairGM was done via extensions, thankfully, not via core changes; in addition to extensions, the skins also played a part — skins developed by ArmchairGM's developers usually implemented some custom handling for the main page of the wiki, for example, while a vanilla installation of MediaWiki with the default skin treats the wiki's main page the same way it would treat any other page.
For your viewing conveniece, here's a list of core MediaWiki files (81 in total) which differ between the ArmchairGM codebase and revision 20138 of MediaWiki:
extensions/README includes/AjaxDispatcher.php includes/AjaxFunctions.php includes/api/ApiBase.php includes/api/ApiFeedWatchlist.php includes/api/ApiFormatBase.php includes/api/ApiFormatJson.php includes/api/ApiFormatPhp.php includes/api/ApiFormatWddx.php includes/api/ApiFormatXml.php includes/api/ApiFormatYaml.php includes/api/ApiHelp.php includes/api/ApiLogin.php includes/api/ApiMain.php includes/api/ApiOpenSearch.php includes/api/ApiPageSet.php includes/api/ApiQueryAllpages.php includes/api/ApiQueryBacklinks.php includes/api/ApiQueryInfo.php includes/api/ApiQueryLogEvents.php includes/api/ApiQuery.php includes/api/ApiQueryRecentChanges.php includes/api/ApiQueryRevisions.php includes/api/ApiQuerySiteinfo.php includes/api/ApiQueryUserContributions.php includes/api/ApiQueryWatchlist.php includes/Article.php includes/AutoLoader.php includes/Database.php includes/DefaultSettings.php includes/DifferenceEngine.php includes/EditPage.php includes/Export.php includes/GlobalFunctions.php includes/Image.php includes/LoadBalancer.php includes/memcached-client.php includes/MemcachedSessions.php includes/MessageCache.php includes/OutputPage.php includes/ParserCache.php includes/Parser.php includes/QueryPage.php includes/Sanitizer.php includes/Skin.php includes/SkinTemplate.php includes/SpecialAllmessages.php includes/SpecialConfirmemail.php includes/SpecialContributions.php includes/SpecialExport.php includes/SpecialListusers.php includes/SpecialLog.php includes/SpecialMovepage.php includes/SpecialNewpages.php includes/SpecialPage.php includes/SpecialPreferences.php includes/SpecialRecentchanges.php includes/SpecialSearch.php includes/SpecialUndelete.php includes/SpecialUpload.php includes/SpecialUserlogin.php includes/SpecialVersion.php includes/SpecialWantedpages.php includes/templates/Userlogin.php includes/Title.php includes/User.php includes/WebStart.php index.php languages/messages/MessagesDe.php languages/messages/MessagesEn.php maintenance/deleteDefaultMessages.php maintenance/dumpBackup.php maintenance/generateSitemap.php maintenance/postgres/tables.sql maintenance/runJobs.php skins/common/ajaxsearch.js skins/common/common.css skins/common/wikibits.js skins/monobook/main.css skins/monobook/rtl.css skins/MonoBook.php
Sure, the ArmchairGM codebase is old and plenty of stuff needs to be rewritten so that it even runs, let alone works properly, on modern versions of MediaWiki.
That being said, I'm glad that the ArmchairGM codebase is now open source — better late than never, as they say.