Just how popular is DayZ, the ArmA 2 modification that has set the game industry, and PC gaming, alight?

A whopping 420,000 people are playing the open world survival horror modification, its creator Dean Hall told Eurogamer after his star turn at Rezzed, the PC and indie game show in Brighton. The alpha version of the game launched just three months ago, in April 2012.

That 420,000 figure is accurate as of today, Saturday 7th July 2012.

Yesterday, Friday 6th July 2012, there were 400,000 players.

Tomorrow, there will be more. "We've got 420,000 now. We'll have 430,000 tomorrow," Hall said.

And next week? Half a million, Hall, who believes DayZ will eventually outsell ArmA 2, reckons.

"Currently we're running 22,000 concurrent at full peak, and 10,000 off peak, which is pretty huge numbers considering the original data structure and system was designed to handle 100 concurrents, and two servers," Hall revealed during his developer session.

"We now have 1000 servers. We're getting 110,000 players in a 24 hour period at the moment."

Hall, who hails from New Zealand, works for ArmA developer Bohemia Interactive as a multiplayer designer. In DayZ, you spawn on a beach and are forced to scavenge for items you need to survive in the world.

"There are no rules. There are no objectives. It was really just designed as a tech demo for something I'd been pitching for a while," Hall said.

The only AI that exists in the game is the zombies. The game, essentially, is about player interaction.

The mod's rapid growth has forced Hall to migrate its server six times. Five servers have been lost to overheating. Every update causes a server crash.

"We have trouble telling the difference between a DDoS and whether some YouTube channel has posted a video of the game," Hall said. "It makes things pretty interesting."

Buoyed by DayZ's success, Hall wants to see it turned into a standalone game, perhaps free-to-play.

Meanwhile, Hall confirmed dogs are coming to DayZ.

"It's just there's a problem with the implementation and there's been so much more that's been more pressing," he told us of the delay.

What breed of dog?

"At the moment, it's a German Shepherd."