Did a second run today, since I lost yesterday's game. Uploaded game_8495 for review. Orthin on Brutal this time.
The Human-Imperial alliance had a whim of stupidity when they decided to declare war on the Orthin while committing their entire fleets to fight the Gremak on the other side of the galaxy at the same time, leaving the Orthin front wide open at the time the war was declared. That seemed like an unnecessary risk. Does the declaration of war logic take into account wether or not the AI can actually ATTACK anything on the turn the war is declared?
Also, found a bug: around stardate 1336 there are two Tinker transports flying back and forth around the Eye of Dzibix - the left-overs of the already-destroyed Tinker empire. I.e. the empire was destroyed earlier in the game, but those transports remained, finally ending up driving circles around their homeworld. The actual bug appeared before stardate 1336, but that's when I noticed the behavior (should help you narrow down the seach a bit, I hope).
The Orthin with their triple-layer battle shields and ultra-fast tech development were a handful this time as well, although I managed to not get killed by them by disconnecting my realm from theirs with outposts. Some of the other AI's were not that lucky. Seriously, the space bugs seemed outright untouchable until the very end, where I started spewing out hundreds of antimatter missiles at them. THAT finally got them. I'm not really sure there is any kind of balance issue here (their fleets were not that large, and certainly did not conquer more territory than the other AI's), but I'm keeping an eye on these guys...
I think the Cloning tech keeps systematically winning me the end-game with council votes. I just need to win a few minor wars to gain population and planets, be diplomatic enough to not anger any of the big players, and breed my way to victory. Maybe that one tech needs a nerf of sorts? In my mind it's end-game-tier tech, but currently comes with a mid-game price and position in the tech tree.
Fleet economy still seems balanced enough. There were some big doom-fleets, but nothing totally over-the-top (albeit that Gremak stack in the beginning of the Human-Gremak war was a handful). Had to limit what I build until I started making my first big conquests on the Gremak front, after that was pretty much swimming in coin (but went into late game at that stage anyway, so it was no problem). Are you planning on pushing this build over the vanilla build anytime soon? It seems pretty finished at this stage - I no longer feel any urge to go back to the old version like I did in the beginning!
One more idea: the Gremak war could have benefited from something like an "unconditional offer of surrender" diplomatic event; the war dragged on for too long. The initial peace offer was lackluster, so I decided the remove the snakes altogether - and ended up fighting in an overly long campaign against what was basically just two ships. Seriously, when the AI has no ships and like one or two systems remaining, it should just be dice down at that stage. Would add a whole new feel of narrative realism. If you want to go wild, add some sort of diplomatic event for handling the peace accords (with different race-specific buffs, debuffs, or the possibility of creating neutral, autonomic states from the remains of the AI empire). The point being, as the AI is losing the war anyway, make its end narratively interesting. SiS could use a little more internal politics roleplay and more diplomatic events anyway. That's the next thing on my wishlist...