So I just ruthlessly dominated a 200-star game of SotS today. I think my ridiculous galactic hegemony came down to two things:
One, the planets that weren't connected by node lines this time were worthless Size 1 blackrocks instead of being size 9 manufacturing powerhouses.
Two, getting AI from Expert Systems.
Combine the two and you have an empire that branches out from one spiral arm of the galaxy and occupies most of the inner core. I grew tired of smashing my enemies for a little while, so I took a break after I had taken a good half of the galaxy, and just decided to tech up so I could make obscenely awesome ships, instead of the Fusion stuff. Heavy Antimatter Cannons are truly OP, and I very much enjoy the noise they shouldn't make, but do, when they fire.
By this point, the three remaining races (me having wiped out the Zuul early in the game because they kept bumping heads with me) allied against me and bum rushed the galactic core. Well, it turns out I have a lot of very nice planets in the galactic core region, so they're all defended by the GOOD defensive platforms, and not just the shitty Destroyer-sized ones. And since that was about where I decided to take a break from the advance of my juggernaut, it was also the front line, so they were tangling with my gigantic front-line battle groups instead of the regional garrison fleets I toss all my older, more lameass ships into.
In the end, it was the Battle of Unicron (yes, Unicron) that had me decide to end the game. They threw a hundred or so cruisers (but oddly, not a single dreadnaught) at my Fifth Fleet and holy shit if Unicron doesn't have a hundred or so destroyed Tarka, Liir and Hiver cruisers orbiting it now. About five turns later, I realized that they no longer had a combatant navy, so I ended up destroying their entire civilizations.
Sometimes, I wish you could just demand a planet surrender to you, but most of the time, I enjoy that the only way to conquer a planet is to burn everyone on it to ash and then build your own colony on top of their burned-down colony (just like the Spaniards).