If, at the beginning, the player is weak, infighting and balance of power between AI empires would take priority over investing resources to wipe out the small player empire.

The player isn't much of a threat, and brutal aggression can have severe diplomatic consequences.

Imagine more rational counterparts of European powers in 1939: the player can be more or less like Poland (or a more peripheral place like Norway), but Germany wouldn't be strong enough to believe in successful world conquest, and invasion attempts would earn them momentary expansion followed by crushing defeat.

Another historical reference: the expansion of the Roman republic and empire due to the high fragmentation of other powers and its inclination for relatively peaceful mergers rather than destruction and extermination. How compatible are alien races with each other?

How compatible are alien races with each other?

1) Uncivilized - insects, bugs, etc, no negotiation possible, you are the food :)

2) Civilized - humanoids, could be assimilated in some cases

3) Smart invaders - no negotiation possible, they want to wipe out the galaxy of all life and take over, they don't find you worthy of assimilation

So, basicly most of the races do not conduct diplomacy and don't care. Only the second group is somewhat compatible.

However "simple", I'm really interested in seeing how the Elders would impact gameplay overall.

Originally, your thread stated that you were looking for a means to keep a balanced level to prevent player annihilation in the early game, yet, the Elders start strong and decline, leaving YOU more room to expand as the game progresses (as opposed to scaling up the difficulty).

While very interesting from a mechanical standpoint, it also seems like it goes against precisely what you've showcased as your primary concern...

Yeah, that post was with my findings AFTER I made a prototype. Making a prototype changes a lot :) Overall, with the latest mechanic (distance + num of planets alien preferences/limits) + starting locations it should prevent the player annihilation... I suppose (need to test it). But if you have further comments on my initial concern (or ideas how to improve the last mechanic I described), post.

Yet, I think I should add some another mechanic to supplement it (not only for the player but also for various AIs, so they are not wiped out too quickly if starting too near each other).