Infestation: Survivor Stories has 1.3 million registered players 

Infestation: Survivor Stories, previously known as The War Z from OP Productions, has over 1.3 million registered players worldwide.

The figure was announced in a press release sent out on the zombie survival MMO, which saw its Foundation Release in December 2012.

Here's some stats:

Over 1.3 million registered players to date
More than 400,000 players log in per month
More than 100,000 players log in daily
Average player has spent more than 95 hours playing
More than 51,119,373 characters created to date
More than 2,248,355,148 zombies killed
More than 52,000 clans created with more than 500,000 players belonging to one of the clans

"We're really happy to see such enthusiasm for Infestation from players as we continue to develop new content for the game," said executive producer Sergey Titov. "We remain committed to providing the best gaming experience for our fans by using community feedback to polish existing gameplay and to help us plan for additional content, which will be released in a large update later this summer."

The game was given a name change back in June.