This is not a joke, viruses also exist for Mac. This is a Trojan that targets users of OS X.
This Trojan called Loosemaque has been updated by researchers at Symantec, and is defined as a threat rather atypical. Loosemaque looks like a video game of yesteryear, site analysis, namely the famous characters from Space Invaders. But when the user destroys the aliens he destroyed along the files of the directory. However, the user is warned that "an alien killed a file is deleted. The user is not caught unawares," the site analysis.
Loosemaque wants to be a Trojan horse designed to "artistic". The game is described on the website that the issue as "a game about choice and consequence, and therefore what it means to succeed or fail." Only here!