Online space-world Entropia Universe is having a party, and the guest of honor is an all-new player avatar system!

SEE Virtual Worlds, the company behind the upcoming Michael Jackson and Universal Monsters MMOs, has purchased Planet Calypso from MindArk for $6 million. In the same transaction, SEE Virtual Worlds acquired the assets of First Planet Company, a subsidiary of MindArk.

Planet Calypso is the first planet in the Entropia Universe. The game's been running since 2003 and has almost 1 million registered accounts. Planet Calypso has a real cash economy; in November 2010, an in-game virtual resort sold for a staggering $635,000. To learn more about the game, check out Senior Staff Writer Chris "Pwff" Tom's recent tour of Planet Calypso.

SEE Virtual Worlds announced late last year that it is developing two new planets to add to the Entropia Universe: Planet Michael, which is based on the life of the late King of Pop, and a world that focuses on famous Universal Monsters such as Frankenstein and Dracula. Players can move their Entropia avatars from planet to planet and explore all of the various MMOs in the universe.

For more details on the acquisition, check out Massively's interview with SEE Virtual Worlds President Corey Redmond.

Are you looking to invest in some virtual property? Do you have a ton of money at your disposal? Even if you answered "no" to these questions, you should take a look at the intriguing sale that's coming up in Planet Calypso, an MMO with a real money economy. The Medusa's Head islands are available for viewing today for potential buyers in preparation for the auction, which will be held from Dec. 13 to Jan. 3. According to First Planet Company, developer and publisher of Planet Calypso, this will be the largest virtual property ever sold.

This sale has the potential to be one for the record books. Last month, a small virtual resort in the game sold for $635,000 after originally being bought for $100,000 in 2005. This piece of property was previously in the Guinness World Records book as the most valuable virtual item.

So what's the price tag on the Medusa's Head islands? Only time will tell, but the property is huge. It encompasses eight different revenue-generating land areas and includes two unique creatures that will be of interest to hunters. You can view a map of the islands after the jump. For more details on this real money MMO, check out our recent tour of Planet Calypso.

For most MMORPGs, it can be rather difficult to find your own niche amidst the hundreds of other competitors; whether it's through a unique combat system or by weaving a compelling one-of-a-kind story, developers are always vying with each other to make their MMO stand out in the crowd. Standing out, however, has never been a problem for the unique sandbox MMO known as "Planet Calypso," which just happens to be the largest real economy MMORPG in the industry while also holding the Guinness World Record for having some of the world's most valuable virtual items.

Entropia Universe's oldest planet, Planet Calypso, just saw the sale of a virtual resort for $635,000. The resort was bought in 2005 for $100,000 landing in the Guiness World Records book in 2008 for most valuble virtual item. It is the Planet's largest asteroid space resort and home to the largely known Club Neverdie. The property is so valuble mainly due to the mining and hunting rights which recouped the $100,000 in the first 8 months after the original sale.

Based on only the virtual property and the profits obtained from mining/hunting rights and property sales, the previous owner's fortune was valued at $1 million in 2006.  The resort continues to allow players access to amazing lands as well as a place to meet and trade.

How much money would you be willing to spend on a virtual item? Read the full press release after the jump.