Space Faring

Home: https://sourceforge.net/projects/space-faring/
State: beta
Download: https://sourceforge.net/projects/space-faring/files
Keyword: strategy, 2D, 4X, space, turn-based
Code repository: https://git.code.sf.net/p/space-faring/gitcode, https://svn.code.sf.net/p/space-faring/code (svn active)
Code language: Java
Code license: GPL-3.0
Developer: Astrometric, Steaker

Quite a lot of design documentation available.

Building