All files in this mod are modified from the game 0 A.D. Empires Ascendant 
(https://play0ad.com/) from Wildfire Games (https://wildfiregames.com/). 
The date of the modification can be seen in the metadata of the files.

0 A.D. is released as open source: you can freely use, copy, modify and
distribute the game's source code and data files, as long as you include
attribution to Wildfire Games and let anyone freely modify and distribute any
of your own modifications to the game's files.
	
The original files are licensed according to this document: https://trac.wildfiregames.com/browser/ps/trunk/LICENSE.txt

Here is the link to the people who contributed to 0 A.D. (not to this mod)
https://trac.wildfiregames.com/browser/ps/trunk/binaries/data/mods/public/gui/credits/texts

The important parts for this mod are that the art files are licensed under:
Creative Commons Attribution-Share Alike 3.0   
http://creativecommons.org/licenses/by-sa/3.0/
see: license_art.txt

And the code is licensed under GPL version 2 (or later)
see: license_gpl-2.0.txt