DAoC was a great game, I get nostalgic just thinking about it. I really liked the idea of taking relics and keeps. I still remember the first time the call to arms went out because an army was spotted headed to the relic keep from Hadrians Wall. One by one, keeps started falling as I was on my horse hoping to get to the frontiers in time to contribute to our realms defense. Just moments prior, I was doing PvE with a group lvling up at Lyonesse and just like that the community at large dropped what we were doing to rush back to twart an invasion.
I also played on a RP server which made it a much more interesting social atmosphere when something went down.
Favorite RvR moment: our guild led a huge force into Alb and dropped every keep (this was old frontiers), naturally convincing everyone on the server that a relic raid was underway. After the last keep dropped we ran the whole zerg to the relic keep and suicided on the guards, ported to Hib, and attacked the relic keep there. We came within a scratch of getting the relic, but it had taken us a little too long to suicide out of Alb because when we arrived at their relic keep we found all the guards were blue and yellow. It was pretty funny to see crowds standing around the guards getting beat on.