Entropia has regularly mixed real and virtual finances.
Online game Entropia Universe has been granted a licence to be a bank.
Issued by the Swedish Financial Supervisory Authority, the licence means the game can be more closely tied to the real world finances of players.
Mindark, the developers of the game, said it aimed to launch a fully-functioning in-game bank within the next 12 months.
At current exchange rates, 10 PED (Project Entropia Dollars) are worth one US dollar.
Unlike many other online games, which charge a monthly subscription fee, the software for Project Entropia is free to download and install.
However, players pay real money to get at in-game items, such as guns, armour and other gear, and the micro-payment system pays for Entropia's running costs.
The licence will make it easier for players to convert real world cash into PEDs and sustain their characters in the game, said Mindark in a statement.
"We will be in a position to offer real bank services to the inhabitants of our virtual universe," said Jan Welter Timkrans, boss of Mindark. It plans to offer players interest-bearing accounts, let them deposit their salaries and pay bills or lend cash via the in-game bank.
The licence also means that each account is backed by deposit insurance to the value of $60,000 (£42,000).
Regulators will get oversight of financial transactions carried out in the game world, so they can spot if criminals are using it to launder money.
Mindark claims that more than 800,000 people have registered to play the game and 80-100,000 are regular players. About $420m of player-to-player transactions were carried out during 2008, according to Mindark figures.