amok: but people say "it is a C&C clone" not "it is a Dune clone", for the same reason why people say "It is a Minecraft clone", and not "it is a Infiniminer clone", the yardstick is not necessary the first, but the one making a genre or gimmick popular or driving it it the point where the genre is (re-)defined. NOt to say that Dune is not a yardstick, as it defines what we think of as RTS today, but C&C did it also.
ucfalumknight: Rereading the OP, I will agree with you 100%. It is hard to differentiate between yard stick games and the game that defined a genre. I think Dune 2000 defined the genre, but C&C is the one that perfected it. Does Starcraft challenge C&C's "yardstick" though. Would most current RTS be compared to SC or are they still being compared to C&C?
It is a little hard to say because the SC and C&C were moving into different styles of RTS. But on the whole I would say SC as because of its pioneering of truly balanced factions.
I think a lot of people in this thread were unclear with what I meant by "yardstick." But Amok hit it on the head. Yardsticks are games that are still fresh in everyone mind. They often do define or redefine a genre but that is not what makes them a yardstick. What makes them a yardstick is that it is a game that we use to judge the quality of another game. Take Doom for example it was a yardstick for FPS for years (even though it really did not do anything that Wolfienstien did not do), For years all FPS were considered to be "not as good as Doom" or "On the same level as Doom." But sinces then it has lost it yardstick status (I would say post Half-life) because no one plays FPS today and compares them to Doom in their minds.