This question already has an answer here:
I recently started playing Hearthstone, and I realized I already knew the correct rarities of different cards without having it explained to me, because I'd seen it before. Stopping to think about it, any time I play a game with items of different tiers of value/power/rarity, I expect them to be color coded as follows:
- Gray - junk
- White - common
- Green - uncommon
- Blue - rare
- Purple - epic/very rare
- Orange - legendary/wicked rare
This pattern, or something very close to it, holds true in games as diverse as Gems of War, SWTOR, Blizzard games (WoW/Hearthstone), Torchlight, Titan Quest, Borderlands, etc.
So what gives? I'm certainly not complaining, because all else being equal, familiar interface design is beneficial. But how did this come to be the standard? What was the first game to use it, and why did it spread?