Nintendo has made great games out of the same half-dozen intellectual properties for more than twenty years. Every Call of Duty game is relatively similar, but the same can be said for most of the Legend of Zelda games. The argument over which game series is better is futile, discuss how the approach, and the respective developers' desired end result is different.
Also look at how each series innovates in their own unique way to meet their consumer's expectations. For example, Zelda is an RPG, so even taking that same game and changing the storyline might be acceptable to appeal to its audience's expectations. On the other hand, Call of Duty is a first person shooter, so people are playing it for the gameplay rather than the storyline, meaning that a new CoD must make marked improvements in gameplay in order to differentiate itself. – OddballGentleman9 years ago