So far I've been loving this game and I just fought the best, biggest, most dynamic, non-scripted battle ever. I'm still playing, the game is on random 10 player, single player, 5 stars, 102 planets(I know, I'm insane). I played as TEC. after about 3 1/2 hours into the game, all hell brakes loose faster than WWII.
I'm doing pretty well for myself, with 13 colonies and ranked number 1 in all 3 major categories, Military, Empire and Economy. I had been in a war with my closest rivals, the Adjun Imperials (Visari) and I had nearly eliminated them. They were a thorn in my side since I started and I had them down to their last planetoid after sacking their homeworld.
I thought that I had a strong ally in the Galan Rim Union (TEC) we had all the treaties we could. I guess I thought wrong, though. 5 of us had been stuck in the same star together and he was conspiring behind my back with the Voice of Senar (Advent). When all of a sudden he declared war on me. I should have seen this sooner as the Advent had a massive fleet gathering in an asteroid field one jump away from my border world, Deinaka. I responded by creating the 3rd fleet and stationing it there. It consisted of a Devon battle cruiser and my flagship Kol class battle ship named Agamemnon.
The Advent attacked Deinaka first, with a massive fleet consisting of many fighters and bombers. My planet lacked anti fighter defenses but I thought that the 3rd fleet could force them to retreat. Then the TEC jumped in, it must have been everything that they could muster because my screen was almost entirely filled with orange. Like any sane commander would do, I withdrew 3rd fleet and was forced to abandon the planet. It never stood a chance.
The 3rd fleet fell back to Gaea, a Volcanic planet that bordered Deinaka but only had 2 jump lanes leading to it. This was my major staging planet and the gateway to my empire, if I lose Gaea, I lose the game. This forced me to withdraw the 1st and 2nd fleets away from the war with the Vasari. I had just defeated their main fleet and sacked their homeworld, they weren't a threat any more.
The plan was to have 3rd fleet hold at Gaea where I could constantly build reinforcements from it's 2 light factories and capital ship factory while the 1st and 2nd fleets maneuvered around to Deinaka and hit them from the rear.
Just as I had suspected, they moved on Gaea next. The Advent attacked first sending their massive amounts of fighters at me. I prepared for this and built 7 hangars and lots of flak frigates to deal with them. Without fighter protection, their carriers and capital ships fell easily to the 3rd fleet. I utterly crushed the Advent's invasion force but it was far from over, the TEC easily had twice as many ships as the Advent.
So I waited, I knew the TEC were going to attack but they seemed to hesitate, this gave my 1st and 2nd fleets time to get in position. They were still 2 jumps away when the attack began. The TEC jumped into Gaea and easily outnumbered my 3rd fleet 3:1, and those weren't fighters either. He had around 5 capital ships and too many support ships. Luckily I had technology on my side. My ships were faster, had better armor and more firepower.
The 1st and 2nd fleet jumped into Deinaka where a small fleet of TEC were guarding their new planet. Around 2 capital ships and a few support ships were guarding it. I left 2nd fleet there to deal with it and had 1st fleet jump to Gaea.
Moments after 1st fleet jumped into Gaea, the computer must have thought, "OH SH**!

I'm surrounded!" and he began to retreat back to Deinaka. I ordered both 1st and 3rd fleets to pursue. His ships jumped way before mine did because they weren't set to jump together. So for a moment, 2nd fleet was on its own against the TEC fleet while my other two fleets positioned to jump.
As soon as they did, the TEC retreated again and fled back to his territory. I wasn't sure if I had taken out any of his capital ships but I destroyed numerous support ships and he was obviously more scared than a little school girl after seeing a spider.
And so I repelled the invasion. That was the most exciting battle I've ever had in an RTS game, It seemed almost scripted. I'm going to try and record a video of the battles and post them on Youtube or something, stay tuned.

Best thing about it is that I didn't lag at all during those battles running at max settings, here are my specs:
Intel Q6600 OC'ed to 3.0Ghz
Nvidia Geforce 8800 GT 512MB
2GB ram
Windows Vista.
I'm sure I'll have many more battles like that as there are still 8 other players left