"Destroy All Humans! is a video game developed by Pandemic Studios and published by THQ. It was released for the Xbox and PlayStation 2 computer entertainment systems on June 21, 2005. The game is set the 1950s in the U.S. and parodies the lifestyles, pop culture, and politics of this time period. The player controls Cryptosporidium 137 (an obvious reference to the protozoan parasite Cryptosporidium), a member of the Furon race of aliens, who has come to Earth to harvest DNA from humans to continue the cloning process of his species. Destroy All Humans! is an open world game."
Source: Wikipedia, "Destroy_All_Humans!," available under the CC-BY-SA License.