However, the auction house in Diablo 3 has stirred huge interest from the so-called gold farmers.

These players make a living by building up huge reserves of the virtual currencies used in popular games. They then sell this for real cash in the game, if possible, or on grey markets if there is no in-game auction house.

Some have gone to great lengths to cash in. Mr Eikenberry recorded an interview with one farmer who was simultaneously running 100 Diablo accounts and claimed to be making about 60 million game diablo 3 gold (about $90, £58) an hour.

The farmer contacted Mr Eikenberry because he wanted Blizzard to fix some of the exploits he was using to cash in. The sheer number of exploits meant rampant inflation was causing the exchange rate of game gold to real cash to crash.

Mr Eikenberry said the farmer was in the "medium range" of those exploiting the game. There were likely to be others running many more diablo 3 items accounts, most of which were stolen from other players, and making lots more game cash.

Diablo 3 was proving so tempting to the farmers, he said, because it legitimised what they did.

"Every farmer dreams of going legit and being able to do business without someone trying to stop them," he told the BBC.

"I'd say 90% of the farmers out there are looking at diablo 3 equipment right now."

This was causing real problems for Blizzard because, he said, Diablo 3 was not designed to be played for hours and hours and hours.

Blizzard had banned some accounts for the most blatant abuse and updated the game several times to make it much harder to exploit. But, said Mr Eikenberry, it would have to keep vigilant to ensure the game was not overwhelmed.