Ugh, AI pretty much completely destroyed my fleets and any chance I had of surviving.
I'm still pretty much a newbie at this game. Just upped the difficulty to I believe one above default as the last game was pretty much a cakewalk.
Started off well, lots of expansion and room to grow. Pretty sure I had the largest overall territory extending from the core to the rim and an OK number of inhabitable worlds in a 400-size elliptical galaxy. Hyperlanes were in an odd, kinda winding path, which did make traversal a bit time-consuming before jumping was an option. Ran into a fallen empire along the core on one side, and marauders on the other side midway between the core and rim.
I think where I messed up was over-concentrating on specializing my colonies, to the detriment of research. It felt like I was struggling to be where I should the whole game, despite being at least equivalent to AI empires. I was able to build up enough of a force to wipe out the marauders before they turned into a horde and went on a rampage. A bit later, after I conquered a small empire off the corner of mine along the rim, I took out some kind of hostile station (forgot what it was called) that was also there.
So, late game. Navy is back up, parked near the fallen empire close to the core just waiting for them to emerge. Stations near the border are citadels built up to max, and a couple more behind the lines to serve as fleet yards. I also have a mega shipyard in a nearby sector and am building up a strategic coordination center. I'm in a federation with another two empires of roughly equivalent power, both also border the fallen and one also with me.
Well shit, back at the rim a couple years away, at the site of that alien station, Unbidden start emerging and taking down systems. There go two worlds and also bunch of trade from surrounding systems. Take my last ascension perk to handle this, and rush my fleets down to intercept. They're not strong enough to take them on directly, but can turtle in the next system as they come one-by-one instead of all at once. Also, my weapons mix sucks as these are all shields/no armor, so I remix my loadout and start cranking out new ships at the mega shipyard and another nearby station while the existing fleets make do. Finally get the crisis taken care of (with absolutely no help from my federation partners). Rebuild the outposts and mining/research stations in the affected systems, and recolonize the decimated planets.
Send navy (probably at ~40-50% of complete) back to the yards at the stations near the fallen empire. Repair and reset the weapons mix back to something more appropriate. Alloys are running low (forgot to reset policy to wartime/military alloy/consumer good balance), so I can't reinforce all at once. Meanwhile, the fallen empire is lurking around in systems on the other side of the wormhole that's in its territory. OK, most everything over there is pretty weak, maybe they'll skip the locals and go straight to the other side of the galaxy, and while they're gone I can swoop in and decapitate them by taking out their home systems (similar to what happened in my last game)? Nope, not a chance.
~10-15 years after my Unbidden crisis, fallen empire wakes up. They don't go after me directly, but instead one of my federation neighbors. So now I'm drawn into this fight to help someone who stood back a couple decades ago and watched my navy be decimated by the Unbidden. I'm not fully prepared. My fleets are at ~75% when this mess starts, and I have no alloy reserves to further reinforce and can't buy enough to make a real difference. I was able to hold them off for a while at my forward-most citadel, but that one eventually fell. Remaining forces fall back to the one behind it. I rebuild for a short while as the awakened empire deals with a federation member on the other side of its territory who took a couple systems. But then it pumps out another OMG huge fleet and comes back for me. Next citadel falls, along with pretty much every ship that was fighting in that system. All I have left are a handful of battleships and cruisers that just came online and are a few systems away. No titans are left, and my juggernaut is also gone. That's it, the game is essentially over, there's nothing I can do to stop the awakened empire from walking all over me.
Like I said, I think (a lack of) research hurt me, my fleet power for its size wasn't where it probably should have been. I let research slide as I over-concentrated on specializing my planets (also not a single relic world to utilize). I tried to compensate later with research habitats, but those where slow to grow despite the robot assembly plants. It also hurt that I had no free spot to take the ascension perk to deal with awakened empires. I'm also not really feeling federations right now.