Planet 51 sees you playing as school boy Lem, or rather not boy, but alien. The aliens of Planet 51 surprisingly live lives not too different from that of humans on Earth, albeit they're green and 'aliens', but otherwise are perfectly normal. The inhabitants of Planet 51 were quite contempt with their lives, that is until an astronaut lands – Chuck, who is surprised to find that he is not alone. He quickly befriends Lem who is tasked with not only the troubles of his own life but getting Chuck back home to Earth whilst being hunted by the alien authorities of Planet 51. The game offers up an open world for Lem to explore and travel through to meet people to do tasks and missions.