No demos? Isn't it a bit too early to advertise a game engine when all there is to show is a github repo?
Edit: Thanks for the link to rescuefox.
Edit: Thanks for the link to rescuefox.
It isn't being advertised that I can see.
Work is being done on github in the open, and some random person saw it and posted it. Or do you know that the poster is involved in the project? (I don't see him/her in the list of contributors, nor in the paladin IRC channel.)
You can try the first one, Rescuefox (not really a game yet, but it kinda works) [1]:
$ git clone https://github.com/mozilla/rescuefox.git && cd rescuefox
$ make
But I haven't looked further than that, so I don't know if its anywhere near functional, but the readme does say
We expect to have live instances of both the develop
and master branches for playing up before too long.