Blizzard Entertainment
On November 23, 2004, Blizzard released "World of Warcraft", a massively multiplayer online role-playing game. "World of Warcraft" is the fourth released game set in the fantasy "Warcraft" universe, which was first introduced by "" in 1994. Blizzard announced "World of Warcraft" on September 2, 2001. The game was released on November 23, 2004, on the 10th anniversary of the "Warcraft" franchise.
Hearthstone
Of the game types they explored, Team 5 soon focused on the collectible card game approach, given that many on the team and in Blizzard had played such games since their introduction. The team found it natural to build the card game around the existing "Warcraft" lore; according to production director Jason Chayes, "Warcraft" was already a well-known property, and the depth of characters and locations created for other games in that series made it easy to create cards inspired by those. They also saw that new players to "Warcraft" may be drawn into the other games through playing "Hearthstone". The team was able to pull concepts and art from the pre-existing "World of Warcraft Trading Card Game", first published in 2006 by Upper Deck and later by Cryptozoic Entertainment; when "Hearthstone" was near completion, in 2013, Blizzard terminated its license with Cryptozoic as to favor their pending digital card game. The addition of heroes, an aspect from the previous trading card game, was found to help personalize the game for the player to allow players to discover useful combinations of cards for each hero.