Gantz  

Gantz - First Stage, Gantz - Second Stage, GANTZ ~the 2nd stage~, GANTZ ~the first stage~, Gantz 1st stage, Ганц, قانتز

If you think your life was difficult, imagine facing death with no hope of salvation or peace. there's no god to save you, only a terrifying reality where you must fight for survival against green aliens and robot monsters. when kei kurono dies, he is thrust into this game - a test of his skills, morals, and will to live. his life becomes someone else's plaything, with no respect given to his choices or beliefs. if he disobeys, who knows what the consequences could be? gantz isn't for the faint-hearted; it contains graphic violence, rape, and greed, reflecting the harsh realities of our world today.

There is also a live action film adaptation that was released in 2011, and a video game by Konami released on PlayStation 2 in 2005.