C-evo is a FOSS turn-based 4X empire building strategy game inspired by Civilization II
(app.zdechov.net)
Screenshots:
Looks like a fork of C-Evo, which has been in dev for around as long as freeCiv. Couldn't find anything about shared assets.
Edit: to clarify, link in OP says this is C-Evo: New Horizons, looks like the OG C-Evo might be defunct.