GANTZ
ガンツ (original)
If you are chosen by the bizarre black sphere known as the Gantz, you are already dead—yet you might be able to reclaim your mortality. First, the Gantz demands that you undertake brutal missions of madness, killing aliens hidden among the population. It is your only chance and you have no choice. You must play this disturbing game. And if you die again—and you likely will—it’s permanent.
It's a animation and action & adventure show, and has a rating of 7.2 out of 10 from Imdb which is usually fine for this kind of show.
Watch it here
Not found streaming from United Kingdom.