"Shadowrun is set in a late future fictional universe in which cybernetics, magic and fantasy creatures co-exist.
Shadowrun typically takes place six decades in the future (2050 when first published, currently 2073). In the backstory of the game, magic and mythological beings returned to the world in 2011. Additionally, some humans changed into orks, trolls, elves, dwarves and even more exotic creatures.
In the Shadowrun setting megacorporations control the lives of not only their employees, but command entire armies (the 10 biggest corporations in the world have extraterritoriality, much like an embassy has now). Technology is highly advanced and cyberware and bioware (cybernetically enhanced body parts or augmented parts grown in a vat then implanted in place of natural organs) are common. The computer crash of 2029 and various conflicts and plagues have reshaped the political and financial landscape of the world. Now when conflicts arise the corporations, governments, even wealthy individuals, and organized crime subcontract their dirty work to specialists, those who then perform "shadowruns" or missions undertaken by deniable assets without identities or those that wish to remain unknown. The most skilled of these specialists, called shadowrunners, have earned a reputation for getting the job done. They have developed a knack for staying alive, and prospering, in the world of Shadowrun.
Source: Wikipedia, "Shadowrun", available under the CC-BY-SA License.