Watching lord british get pwned during the beta was pretty cool.
I'd have to say as far as MMO's go, my cool moment was getting hand of ragnaros.
I won a weekly Warcraft 2 LAN Tourney back in the day for a few months straight at a LAN center I used to hang out at, I felt like the king of the video gaming populace, This kid used to watch me play every week, then once he got to know how I played, entered against me and beat my ass. it was a rivalry from then on out, we'd trade wins week after week, we were pretty much equals at it
Yes I said warcraft 2 and LAN, I'm an old fart.
Basically my strat was to establish town halls all over the unclaimed mines with a couple towers to defend against scounts
do the tech tree up until I could make Knights, build 3 sets of barracks in 3x3 formation (27 unit production facilities)
then just click, hit the knight hotkey, 27 times, send all of them at the enemy
repeat.
it's just swarm after swarm of heavy calvary.
it worked so well because most people were turtles and the knights could move fast, take out most ground units with ease, and 27 of them against the average tower configuration meant that even if the 1st wave died, the towers would be a mess by the time the next wave hit.
that and most people only built like 1 or 2 barracks, I stopped doing that cuz I realized I was making gold faster than I could spend it.
he countered me by building squads of infantry/archers and just trying to pre-empt my town hall expansion efforts by setting up barricades outside of my bases. then he'd get siege weaponry to take out my towers and just move in his wimpy little guys to harrass my peons before my knights could get in to play.