Hearthstone, the digital card game based on the Warcraft universe, has reached the milestone of 70 million registered players.

In celebration of the feat, Blizzard gave away free packs of the game's latest expansion, the dinosaur-themed Journey to Un'Goro, to all Hearthstone players.

'Hearthstone' Hits 70 Million Registered Players

Blizzard announced that Hearthstone has welcomed more than 70 million players through a blog post on Battle.net.

Hearthstone reached 30 million players in May 2015, which means that in a span of two years, the digital card game was able to more than double its player base.

To celebrate the achievement, Blizzard decided to give away three free Journey to Un'Goro card packs to all players. The free card packs are available for both new and old players.

To receive the free card packs, players will only need to log in to Hearthstone with their accounts. The free packs can be claimed until the end of May.

"We look forward to sharing many more years of Hearthstone with you. Hold on to your mug, and let's find out where the journey will take us, together!" Blizzard wrote to end the blog post.

'Hearthstone' Popularity Hits All-Time High

The achievement of 70 million registered players is not the only milestone that Blizzard announced for Hearthstone. The company also revealed that the popularity of the digital card game has reached its peak, with more gamers from around the world playing in a single day compared to any point in Hearthstone's history. Blizzard, however, did not reveal a specific figure.

Blizzard attributed the all-time high in popularity for Hearthstone to Journey to Un'Goro, the latest expansion, which was released last month.

Journey to Un'Goro is an expansion that features an ancient jungle filled with primordial creatures, including dinosaurs, elementals, and flesh-eating plants. The expansion added 135 new cards to the game, including a handful of new mechanics.

One of the main mechanics of the expansion are Quests. Each class in Hearthstone received one Quest each, and they always show up in the player's opening hand. The Quests require players to achieve a certain requirement, which will reward them with a game-changing card or effect.

Blizzard Revamped 'Hearthstone'

The Journey to Un'Goro expansion, however, may just be a part of what pushed Hearthstone's popularity to greater heights. Blizzard implemented several changes to revamp the digital card game before the expansion's release to address various issues that players have pointed out.

In February, Blizzard nerfed two cards, Small-Time Buccaneer and Spirit Claws, which were important pieces to the dominant Pirate and Shaman decks, respectively. Blizzard also made changes to Ranked Play to make the climb up the ranked ladder easier for players.

Shortly afterward, Blizzard revealed that several Classic cards, including legendaries Sylvanas Windrunner and Ragnaros the Firelord, were being moved out of Standard and into Wild. The company also announced that the 45-card adventures will be replaced by 130-card expansions, bringing the total number of expansions for Hearthstone per year to three.

Blizzard continued the Hearthstone revamp by switching Arena mode to a Standard format and making several tweaks such as reducing the number of common cards and increasing the chances of spells in drafts.