Ever noticed how every time a new game comes out, a new feature gets added or a new expansion is released, people always go "OMG, they just copied/ripped this off of (insert copied game here)!!" ? I know I've done it a few times myself but recent events made me rethink the matter.
Every time we do a new publish, some players always find a way to look at the Clilocs to get some spoilers as to what is upcoming. Sometimes, what they see is indeed new content, but sometimes they just see work in progress or internal stuff that will never get in the game. In that specific instance, they saw a new reward I was working on for a future publish. Someone made a comment on the board about it being a rip from World of Warcraft. My initial reaction was "huh?!" but after further thought, I could see how that player would think that.
But while WoW indeed has something similar, this reward was simply a beefed up version of a UO item that existed long before anyone ever heard of WoW. The change is essentially increasing its duration and the buff it provides, making it useful again. So why did the player consider it a WoW rip off? Because the current UO version didn't keep up with the evolution of the game and is obsolete at the moment (hence the revamp it's getting). The majority of UO players isn't even aware it exists while the WoW version is a commonly used item. You could almost say WoW made that type of item popular.
So would it be fair to say that WoW copied its version from UO? Maybe, maybe not. I would lean towards probably not. In truth, how do you determine who rips off of who? Who had the original idea of whatever?
Most games could be called a rip off of an older game. What RPG didn't steal something from D&D? What FPS didn't take from Doom or Duke Nukem? What sand box didn't copy from GTA? Which came first? The chicken or the egg? Does it even matter? A perfectly roasted chicken is just as good as a nice omelet. I wouldn't put chicken in my bowl of cereals, but I wouldn't make a cake without eggs.
There are only so many ingredients to go around. And any way you cut it, there will always be flour and eggs in a cake. Regardless of the amount or type of flour, you will put some in. Whether you put icing on the cake or not, is up to the cook. Replacing the cherries by strawberries in a black forest cake doesn't make it a strawberry shortcake. But you have to ask yourself if the strawberries really belong there or are they just going to go by unnoticed, buried by the overwhelming flavors of the other ingredients.
In the end, the ingredient itself doesn't matter as much as what it's being used for and where. As long as it makes sense, tastes good and doesn't transform your cake into something it wasn't meant to be, then go for it.