Hello,
Thanks for pointing that out. I realized the wording in the credits file was misleading.
When I wrote that players were allowed to create mods and improvements, I wasn't referring to modifying the game's source code. What I actually meant was that players are free to replace and customize things like sounds, translations, and other user-editable resources, and to share those with the community.
I'm still fairly new to game development and licensing, so when I wrote the credits file I didn't fully understand that the word "mods" usually implies source code access or an official modding system. That wasn't my intention.
The game's source code isn't public, but I'll update the credits file in the next release to make this much clearer. Thanks for bringing it to my attention!