Card games are an important and growing market in video games worth $1.3 billion in 2017, research firm Superdata reports, and should hit $1.7 billion in 2019. Blizzard’s Hearthstone rules, making 3.3 times more than its closet competitor. But it's going to get a serious competitor when Wizards brings Arena from its open beta to launch state and when Valve releases Artifact, its take on digital card games, on November 28.