ok finished my game as clan of embers (world successfully destroyed). Here's the balance feedback.
Firstly and most importantly: getting 100 on the armageddon counter doesn't seem to have any particular benefit to evil races. seeming that hitting 100 devestates ALL races, what's the point? As the dominant player in the game, having killed off all opponent's heroes, the 100 event would do nothing but hurt me. In the end the infernals triggered the event, but I found it much more lucrative just to sit the counter on about 97.
I think the 100 counter event should ONLY effect good/neutral races. That way it actually gives the evil races a game-winning advantage, rather than just knocking everyone back to square one. I don't think this would be unbalancing, considering a) how difficult it is to get the counter that high and b) it is supposed to be a game winning event for evil.
Other than that:
The whole barbs declaring war on you if you get too far ahead in points is lame. really lame. Apart from being really annoying, the mechanic is also broken. Just get a friend, pump his score and then kill everyone else. In the game I just played, I had to constantly rush units and gift them to the calabim in order to remain at peace with the barbs (prince difficulty) and even then I only just managed to win in time, seeming that all four horsemen AND the avatar of wrath spawned within a tile of each other right next to them. As I said, lame mechanic, dispose please. The -10% research is already a horrible enough disadvantage for the barbs trait.
and finally
There's not enough of a 'great alliance' feel atm. As clan of embers, I managed to trash all the other 7 good/neutral races, and was about +30 with hyborem and alexis. However, once the counter had hit 100 and all the good races were gone, the game just kind of stalemated. Neither hyborem nor alexis would agree to a permanent alliance (despite me singlehandedly keeping both of their civs alive) and I had to just twiddle my thumbs until I won a religious victory by inquisitioning the OO out of calabim cities (they were veil but had converted from OO originally). Boring.
Maybe make it so that, once all good/neutral races have been destroyed, and the counter has reached high 90's/100's (or visa versa for good races maybe), there is some kind of easy to complete ritual or event that auto-allies all races of the same religion, thus completing the game without having to turn on your friends/win by tower of mastery/religious victory? Otherwise, maybe have civs of the same alignment/religion way more likely to enter a permanent alliance- remove the defensive pact or shared war for 100+ turns or whatever it is restriction.