I never thought to do this, but now that I have…
Here's a look at various card games and the size of their Reddit community:
Magic - 50,231 Subscribers / 4 years old
Yugioh - 6,704 Subscribers / 2 years old / This includes all things Yugioh and not just the card game. Somewhat of a misrepresentation.
Pokemon - 1,988 Subscrubers / 2 years old
Netrunner - 1,199 Subscribers / 1 year old
Legend of the Five Rings - 235 Subscribers / 1 year old
Star Wars LCG - 94 Subscribers / 4 months old
Star Wars CCG - 22 Subscribers / 1 year old / DEFUNCT
Shadowfist - 22 Subscribers / 6 months old
Vampire - 20 Subscribers / 1 year old / DEFUNCT
The Spoils - 20 Subscribers / 1 year old
AGoT - 10 Subscribers / 9 months old
This list even surprised me a little. There are two defunct games that have more interest on Reddit than A Game of Thrones. Magic has 5000 times more interest than AGoT. Netrunner has 100 times more interest. Star Wars LCG has 10 times more interest. Even the two defunct games have twice the interest. I'm not totally shocked Pokemon is higher than Netrunner, but I was mildly surprised.
I wonder how these numbers would change if the active AGoT community actually moved over there.