Gantz tells the story of Kei Kurono and his friend Masaru Kato who die in a train accident and become part of a semi-posthumous "game" in which they and several other recently deceased people are forced to hunt down and kill aliens armed with a handful of futuristic items of equipment and weaponry.
This is dark and sad at times. But its the truth it shows us the kind of people you find in the world. This anime is awsum theirs action romance and so much more fighting giant aliens with cool looking space suits!. I would suggest if you want more of this too just read the manga as the manga goes into the story deeper and doesnt have that crappy last arc. The manga goes on for much longer then the anime. Dont know why it didnt have a longer anime its pretty popular and just epic.