Blizzard claims 'Diablo Immortal' is the "biggest launch in franchise history".

The free-to-play MMO game was released on June 2 on iOS and Android, and according to the company says it's the most succesful game, with 10 million installs in just one week.

The official Diablo Twitter page tweeted: "Shoutout to the heroes of Sanctuary.

"In just one week, Diablo Immortal is the biggest launch in franchise history.

"Thanks for slaying with us."

It's not been plain sailing, however, with the game receiving a backlash from gamers for its ‘pay-to-win’ microtransactions.

However, the game's director Wyatt Cheng responded to the criticism: “In Diablo Immortal, there is no way to acquire or rank up gear using money.”

However, it can be used to upgrade a character.