Pacifist: In isolated system with a unique gateway nearby....Opened though event chain midgame? Fallen empire has no fleet? But has or owns a leviathen?.

Militarist: Large fleets, max starbase, unique techs?, use enigmatic fortress for something? Fleets of only titans? Strategic coordination centre?

Uses special war goal to kill normal empire fleets/ to make battle? When unawakened?

Authoritarian: Thrall worlds, tomb worlds, lots of slaves. Midgame event or if declared upon, where the slaves can rebel and player can help them to increase their chance of winning or help the fallen empire win?

Egalitarian: Mega Art Installation or Interstellar Assembly or both? Ruined but can be rebuilt by midgame event where the player can help. War goal to change governments to democracy when awakened?

Maybe a militarist/xenophobe one (maybe even fallen fanatic purifiers? although the war goal might cause issues if it can't properly be limited to lategame without changing the civic itself) that stays dormant until the midgame, then demands territory from neighboring empires (like, empires that are up to 3 systems away or something), like 1-3 systems or so every once in a while, backed by threat of war if the demands are denied, but supported by increased friendship and decreased likeliness to have something demanded if accepted. Maybe sometimes also demands you become a vassal or tributary if you're within like 5 systems. And then, in the lategame, it could just get a free war goal reminiscent of fanatic purifier's "purification" one, and awaken automatically if it hadn't already.

edit: i know it's a little extravagant, but i figure it's better to spitball some crazy ideas that can be picked apart to make something cool and feasible.

I like the sound of it, i'm just imagining the work I would have to do :D

Though your post does remind me that there isnt a hive mind fallen empire yet.

Could be dormant, ie doesnt exist until a dig site event chain is completed.

When it awakens turns into a devouring swarm?, maybe uses scourge shipset?

For Fanatic Egal. FE, I'd suggest making a ruined Assembly. Art Installation is more fanatic xenophile structure I feel (as they would appreciate the art of alien cultures). In the mid-game It starts demanding that authoritarian empires or empires with centralized governments make concessions to it (influence/unity debuffs) under threat of war. It also gives free fleets and resources to egal/xenophile empires be they player or AI. Maybe those empire types also get a influence/unity buff opposite of the "tyrannical" empires? Upon end-game start year it checks for any slaver empires, bandit empires, or fan authoritarian empires and if at least 2 empires in the galaxy are one of those three types, or 2 empires are both of 1 of those types, it awakens as a "Resurgent Republic".

Upon awakening, It will request that all egal/xenophile empires become "Sister Republics" (new FE vassal type specifically for this one) which means they become fan egal. and all species rights are set to "Full Citizen" and are locked in. These subjects pay nothing to their overlord and must enter their overlords wars. Once all egal/xenophile empires have been asked at least once to become a "Sister Republic", the "Resurgent Republic" will declare a war of ideology on the closest enemy empire (slavers, fan auth, bandits) to it. It will always be hostile to marauders but will ignore them unless it passes through their territory.

Just some thoughts.

Originally posted by MayhemX8:

For Fanatic Egal. FE, I'd suggest making a ruined Assembly. Art Installation is more fanatic xenophile structure I feel (as they would appreciate the art of alien cultures). In the mid-game It starts demanding that authoritarian empires or empires with centralized governments make concessions to it (influence/unity debuffs) under threat of war. It also gives free fleets and resources to egal/xenophile empires be they player or AI. Maybe those empire types also get a influence/unity buff opposite of the "tyrannical" empires? Upon end-game start year it checks for any slaver empires, bandit empires, or fan authoritarian empires and if at least 2 empires in the galaxy are one of those three types, or 2 empires are both of 1 of those types, it awakens as a "Resurgent Republic".

Upon awakening, It will request that all egal/xenophile empires become "Sister Republics" (new FE vassal type specifically for this one) which means they become fan egal. and all species rights are set to "Full Citizen" and are locked in. These subjects pay nothing to their overlord and must enter their overlords wars. Once all egal/xenophile empires have been asked at least once to become a "Sister Republic", the "Resurgent Republic" will declare a war of ideology on the closest enemy empire (slavers, fan auth, bandits) to it. It will always be hostile to marauders but will ignore them unless it passes through their territory.

Just some thoughts.

Big up this one!

Idea is stolen ( i saw something similar somewhere once)

A fallen hivemind that falsely believes all species in the galaxy to be its drones (and calls them "autonomous drones" or something). It will randomly demand tasks (give x minerals monthly for 5 years, colonize x planets in schedule) and act as if it is planning everything.

Once it awakens it realizes that it's actually just a vestige empire and does not, in fact, control the galaxy and tries to assimilate everyone "back" into the hive.

Systemwise it resides on a few hive-worlds with different species labeled "agro-drones" "mining-drones" etc.

perhaps a marauder fallen empire?

(prob wont have any ethics tbh similar to current marauders)
once a proud khan-like empire that spanned a large portion of the galaxy, they eventually fell to outside powers and secluded themselves within a few systems. They've been idle ever since then, contempt to finally quell the inner conflicts within their borders.

would have at least 3 star systems, living in several orbital stations similar to other marauder empires, but will have one colonized world, being the capital called "Plunderer's Throne". They will have a ruined mega-shipyard.

Will occasionally demand resources from other empires in exchange for a couple pops they've designated as "disgraced/exiled criminals". if empires refuse, they won't declare war, but instead send a fleet to raid worlds for a while, and possibly forcefully colonize a habitable world within your borders with their "exiles". These "forced colonies" will have 3 criminal pops with the planet having 100% crime and 0 stability. These 3 pops will either have authoritarian or xenophobe ethics.
will immediately rival the great khan, and will attempt to raid khan territory. however, their fleets will still be hostile to other empire's fleets.

once awakened, it will try to subjugate nearby empires and will declare war on anyone closer than 5 star systems away to claim territory. It will not be a guardian, but will attack crisis fleets near their borders no more than 5 star systems away.

A dormant machine empire similar to Necrons from warhammer 40K, except that can spawn on a random planets / select cluster of planets, disurbed into awakening via certain events or digsites which the AI could open as well. 'Necron' strength is dependant on weather its early mid or late so as not to steamroll the galaxy only 20 years in.
Could awake as assimilator or exterminators possibly depending on choices made. Can be shut down before fully awake if acted upon (situation mechanic) but very difficult to purge from your planet as they sleep in underground tombs spanning the entire world