License is unclear
As noted by @MCMic, it's unclear what exact license applies to JAG.
On the SourceForge page, it states: Qt Public License (QPL), GNU Library or Lesser General Public License version 3.0 (LGPLv3)
The original code is here: https://sourceforge.net/p/jag-game/code/HEAD/tree/
There, the readme mentions:
This software is free and is distributed according to GPL and compatible licenses. Full text of GPL and more you can read here: http://www.fsf.org/licensing/licenses/gpl.html
On the archive of the original website, there is no mention of the actual license.
In the AppData file I added, I seem to have assumed GPL-2.0+, but not sure where I took that from.
I was in contact with the original developers in 2015, I'll try to contact them again to get a statement on the license.