Blizzard Entertainment's Hearthstone has reached 100 million registered players just over five years after launch. 

Hitting 100 million players is a notable feat for the developers, considering how quickly its grown and changed throughout the years.

The competitive card game clocked in more than ten million registered players less than a month after its official PC debut before moving on to mobile, which brought new challenges for the developers as they navigated a new platform.

To celebrate the milestone, Blizzard is presenting players with free card packs and an in-game event which will run from November 7 at 10:00 am PST through November 11.

As explained in a blog post, players who log in during the event will receive six free "The Boomsday Project" card packs with the chance to earn up to 500 gold, as well as a "Celebrate the Players" quest.