Hearthstone's next single-player expansion is expected to go live in April, according to a new report with details from a purported insider at Blizzard.

An article by Yahoo Finance contributor, Tae Kim, suggests that the new Hearthstone content update will be "PVE focused", which suggests it will be a similar proposition to the Naxxramas update that shipped in July.

These single-player expansions pit players against toughened AI, and if Naxxramas is any indication, against heroes who use unique cards and abilities to swing the game to their advantage.

Blizzard has declined to comment on the rumours.

Tae Kim, who says his information comes from am employee at Activision Blizzard, also claims that Hearthstone's user numbers have rocketed since September, when it was revealed that the game had accumulated some 20 million players. Since then, the collectable card game has expanded with Android support, as well as the major Goblins vs Gnomes expansion.

According to the alleged Blizzard employee, the game has now surpassed 75 million players. The user numbers were described as "off the charts."

[Update: New official statistics from Activision Blizzard show that this estimation of player numbers is wildly inaccurate. According to the publisher, Hearthstone had accumulated more than 25 million registered players by January 2015.]

Meanwhile, it's claimed that the Hearthstone team is "also experimenting with a 2 vs 2 version". It's not clear whether this means two heroes versus two, or a pair of players sharing command of a single hero.

GameSpot has contacted Blizzard for further clarification and comment.

Hearthstone won GameSpot's Mobile Game of the Year award in December, and was a nominee for overall Game of the Year.