Was posted on #freegamer on freenode:
http://shuvit.org/grav/
Seems pretty cool, although not really my type of game. Hence I didn't investigate it much yet.
CC0 licensed (?) source and assets (incl. .blend files!) can be found here:
http://gogs.shuvit.org:3000/Shuvit-Org/shuvit
And I was told it is based on the https://upbge.org/ engine (which is integrated very well with Blender).