What's JA2v1.13 about?

In short:

The last official version of JA2 is 1.12 (gold). Stuff hapened and the source code was released to public. Fans picked it up and continued development. One of those developments got called JA2 v1.13.

It offers bugfixes, quality-of-life changes, more weapons and items, more mercs and a lot more features (can be turned on/off).

It can be played as stand-alone-version, but it also serves as mod-plattform. This is a thing, because the developers of 1.13 externalized many things (to files like .xml, ini, etc. in folders of 1.13-Game-Directory)

As a result, many stuff former only available in code, is now accesable to everyone - and since everyone includes modders, there are already many mods (modifications) which use 1.13 available.

Therefore, beside being able to play JA2 v1.13 as standalone, one can also play those mods with 1.13 used as base.

Some mods change and/or add maps, some change the story and the quests, some add even more weapons and items and some do all of it at once.

Follow link at bottom to get download-links (1.13 and mods) and more descriptions

What about different versions of 1.13 you may have heard about?

JA2v1.13 still gets further developed even today. The very latest version is often also called "unstable". That's a rather misleading name. It's refering to "under constant development", not to being full of bugs. The opposite is true, that's the version with most bugfixes.

To make the confusion worse, there is a version of 1.13 which is called "stable". That's the version 7609 of 1.13. It's from 2014 and at that time, developers put that version aside to give modders a version to work with without being constantly changed, hence called "stable".

The 7609-version is interesting, because it is used as base-version by many mods, the latest version is interesting because it has most new features and even more bugfixes then 7609 (which already is running fine).

How to use those 1.13 versions with JA2 from Steam?

First, instal original JA2 from Steam.

Open Steam-Folder on PC (if unchanged, it should be in "Programs" or "Programs x86")

At Steam/steamapps/common look for folder "Jagged Alliance 2 Gold"

Copy whole folder and paste it somewhere not directly Windows (not "Programs" or alike, maybe D:\\Games\\Jagged Alliance 2 Gold)

Make a backup-copy, to avoid doing this again (one can have multiple JA2-instals at once, even runs from USB-stick, makes no registry entries)

Download 1.13-version you like to use, unzip it, copy content of unzipped into JA2-original, overwrite when asked

So, basically it's just copy and paste.

Where to get 1.13 versions?

Take a look at the Bear's Pit Forum, home of the 1.13 developers

Link: How to get: latest 1.13, 7609, feature-descriptions and more [thepit.ja-galaxy-forum.com]

There are:

download-links,
more detailed description on how to instal (if needed),
further descriptions on different versions,
feature descriptions,
a bunch of other useful informations,
help with performance problems on Win10 (slow, resolution)
links to mods,
link to Bear's Pit Discord for quick answers