OpenArena eXpanded (short: OAX; also OpenArena eXpansion) is the non-engine development of Open Arena.
What is OAX? Edit
These "beta" releases are previews of what will be OpenArena in the next official releases and are distributed as mods for easy testing.
In these betas you can find, for example, new game options, changes in the user interface, and in the rules of the gamemodes.
R and BEdit
It's possible to find two different OAX numberings: "R" and "B" versions. "R" stands for "revision" (a.k.a. "rev"): each time a developer updates the source code/files on the "svn repository" (in short, makes a change), the "R" version number goes ahead; this allows to track each change, but you need "the hard way" below to test these latest changes. "B" stands for "beta": once on a while, a developer creates a "beta" package (starting from a specific "R" version) that everyone can simply download and test in "the easy way", like a mod; these downloads may miss the very latest changes, done after their creation. An OAX B version number is lower than the corresponding OAX R number, since a new beta package contains the changes introduced with more revisions; as an example, Beta 47 is based on OAX r238.
Where to find it? Edit
You can find news about OpenArena Expanded here. It contains a download link for the source code and the "playable mod" version, description of the changes for each beta version, plus that thread is the place you can give feedback for them.
Furthermore, when a big change is implemented, so the engine must be touched, the thread about the latest test binaries is the place to go in order to download the latest binaries.
The easy wayEdit
- Go to the forums, to the thread about OAX.
- Download an OAX Beta version "mod"
- Unzip it inside your OpenArena installation folder (or user settings folder), so you should obtain a subfolder called "oaxBXX" (where XX is the beta version number, for example "oaxB45" for Beta 45, "oaxB46" for Beta 46... you can have more OAX beta versions "mods" installed). 
- Start OpenArena, then select "Mods", and there choose "oaxBXX"
- Use the game and try it. Please refer to the "readme.txt" file or to the thread on the forum to know what's new in each beta version.
The hard wayEdit
To test the very latest changes (the ones that can be viewed in the changelog) you can checkout from svn and compile yourself. This is also relevant if you want to make your own changes or tests.
- Install a subversion client. In Ubuntu Linux this is done with "sudo aptitude install subversion". In Microsoft Windows must use TortoiseSVN software.
- Checkout with "svn checkout http://oax.googlecode.com/svn/trunk/ oax-read-only". In TortoiseSVN http://oax.googlecode.com/svn/trunk/ must be entered as address like this:
- Compile. In Windows run windows_compile_game.bat, windows_compile_cgame.bat and windows_compile_q3_ui.bat in "windows_scripts". This will create a folder called "windows" with a subfolder called "baseoa". In "baseoa" is a folder called vm. Compress vm to a zip file. Call it oaxdev.pk3 copy it into a oax-folder next to baseoa where you installed OpenArena. Linux users can use the "supermake"-script in "linux_scripts" to compile, pack and launch the game in one command.
- Start the game select oax as a mod. Unless you use the "supermake"-script as that will also launch the game with the mod active.
Coding tutorials and resources Edit
Submitting changes Edit
If you have developed a change, as long as it doesn't violate NOTTODO, propose it in the OAX thread.
- ↑ Note: this folder goes at the same level of the "baseoa" folder, not inside it... and do not mix the files from the mod with those in baseoa. It is very important to avoid placing modified gamecode in the baseoa folder, especially if you are running a server that other players will be able to connect to (you may mess up their OA installation!).
- Old forum thread about "Elimination" (old name for OAX mod, up to beta 21)
- Current forum thread about "Open Arena Expanded". You can get the latest beta version "mod" in the first post.
- OpenArena Expanded on googlecode - Update list (running change log)
- TortoiseSVN and its article on Wikipedia.
- The Wiki Pages of OAX - They contain some help about some features of OpenArena.
- OpenArena Server Administration help on the Wiki Pages of OAX.
- "Issues" section of the OAX site - Sort of bug tracker.