I lost once...and I lost really badly...I was the yor...and I was pretty much in the middle of my 5 opponents...now, the Drengin were one of them. So, I did a mass colonization of a huge chunk of space, and was well on my way to becoming an unstoppable force, my techs were soaring, and I was just getting into building up my military (about 10 more turns, and I would have been quite strong).
Then the Drengin declare war.
At first, I'm thinkin no sweat...and I mass produce what I can ship wise to coordinate my defense. 3 rounds later, I'm outnumbered, and outgunned (their ships were larger, and better armed). I put up almost no real defense...next thing I know, about 10 troop transports come in and take my key planets...I lost rather swiftly
I loved it...teach me to think myself unbeatable. Those ten rounds made all the difference, doh!