Starcraft!
Ah, Starcraft. The undeniable king of RTS games. Great campaign and story, and nearly infinite replay value on Battle.Net- people are still playing a game that came out in '98, even if most of the people left on BNet are the shitty remnants of a once great gaming community. I still play regularly, but I play almost exclusively Use Map Settings games.
Now, I don't have time to explain the finer points of Starcraft strategy to you, but I'll give it a shot.
Mass Carriers, the strategy of any idiot newbie who realizes how easy it is to win, is NOT undefeatable. Lockdown, Dark Swarm, and as always, Mass Battlecruisers work well against the carriers.
An important thing to remember about game rules is that they don't have to apply to you if you don't want them to. Some guy wants to mass carriers, says NR 20? Who cares? Demolish his base at the 10 minute mark- winning is still winning. Don't let yourself be bound by rules- that's playing the way the host wants you to play.
That's as far as I'll go today about Starcraft. Feel free to find me online on BNet West - Username is t4c0b3ll.