The first full expansion to Blizzard's digital collectible card game Hearthstone: Heroes of Warcraft will add a huge number of new cards.

Speaking with Polygon, production director Jason Chayes said Blizzard will "mix it up" in the first expansion.

"It will have a lot more cards. We’re talking about more than 100. We are going to have a central theme for how that will all fit together. That’ll be the next thing coming up."

Chayes said that Blizzard frequently discusses how best to pace the delivery of new content.

"We really want to make sure the pacing is great not just for seasoned Hearthstone players but for new players coming into the game too," said Chayes.

"We really want to pay attention to how that is for the entirety of the player base. Does that feel like the right amount of content? Is it too little? Is it too much? We feel like this is a good starting point."

Hearthstone came out of beta on PC and Mac in March. The free-to-play collectible card game is also currently available on iPad.

Hearthstone is coming to Windows 8 tablets, iOS phones, and Android devices later this year.

In July, Blizzard released the first singleplayer adventure for Hearthstone, called the Curse of Naxxramas. The full expansion adds 30 new cards to the game that are earned by defeating bosses, with completion of each wing guaranteeing the player a new Legendary class card.

Curse of Naxxramas has its own unique game board, as well as nine class challenges that require players to duel using a predetermined deck.