Not sure if Galciv1 counts, but I'm sure everyone of that era can remember the 10,000+ bc trade routes.
Also there was the time I would sell an AI one of my planets for a bunch of money, then turn around and invade the planet I just sold...steal a tech....then in a few turns sell the AI I invaded a peace treaty, for more money. Go to the next AI, repeat.
There's the time I built early starships and blasted every colony ship, every miner, every flagship I saw. I had a good colony rush that game. Don't know why.... I never bothered negotiating peace with anybody--I just remained at war with the whole galaxy the entire game.
There's the Korath spore rush--I just pretty much forgot about the colony rush. I just let everybody else colony rush while I went straight to Spore. THEN I decided to "colony" rush--with my Spore ships. They never even had a chance to build orbiters. hee hee hee hee.... I got 3 AI home worlds that way.
Then there's Apocalypse in the DL Campaign. That was just epic.
On the flip side, there was the last scenario in that same campaign where the entire scenario consists of buying several transports using Mitrosoft and invading everybody within 6 months. It was nice ripping off Mitrosoft and their 192-turn leases for a change--the game was over in 20 turns.
There was this bug in Galciv1 where I used Info Warfare and I ended up with a planet with 100b population. 1% morale.
I just sent all my empty transports to that planet for soldiers and invaded the rest of the galaxy with it.
There's the time I built some fast Survey ships, cargo hull. I wound up upgrading them with weapons and lots of defenses. 1 hp hulls. Those babies were invincible. 
There's the time I won a free copy of Galciv2. But I already had Galciv2.
I have two copies registered on my account to this day.