In the beginning, you got a great mix of people. Many of them die from mission to mission, but you still have a good core group that keeps surviving (mostly). The bonds (or lack of) between them is what really makes the series. The first few hunts are kinda lame, but it starts to take off quickly after that. There's a great sense of pacing in this manga, from the lightning fast fighting scenes, to the slower paced day to day scenes of people just being themselves and living otherwise normal lives. After a while the fights become incredible and other weapons are unlocked after getting 100 points. Including a mecha power armor. Fuck Yeah!!!!!

Then for some reason the plot goes crazy. You find out there's a countdown in place, and that the gantz balls are produced by some mysterious company. The possibilities seem endless as to where things might go from here. Then you find out that the countdown is simply for a lame ass alien invasion. FFFFFFFFFFUUUUUUUUU!!!!!!!!!

When I left off the invasion was in full swing. It really only lasted 5 chapters, and earth lost so fucking hard. Now the gantz players from around the world are in a campaign of guerrilla warfare for various reasons. The main character in trying to find his girfriend on some alien ship, who is by far the dumbest cunt to ever be written in any manga ever. If anybody here has read Bleach and is familiar with Orihime's horribleness as a character, I assure you this chick if 5000% worse. The Ichigo-kun, Ichigo-kun, Ichigo-kun antics from Orihime pale by comparison.

What's worse, nothing ever got explained. Where did all these various monsters, aliens, and vampires even come from. How does the organization fit into all this. What's the purpose of even bringing people back to life to fight in these competitions in the beginning.

Truly one of those "Da' Fuck am I even reading" mangas.

The vampires came from special nano-machines being released upon the population which gave them a condition similar but not exactly the same as that of "traditional vampirism." I can't remember if the concept of vampires existed before like how it does in our universe, and then the nano-machines coincidentally or maybe not-so-coincidentally gave humans such a condition, or if the term vampire just never existed in their universe until the condition with the nano-machines happened. Of course, it's not completely explained as we don't know where the nano-machines came from exactly, or even where the only two vampires left that we know of are at currently in the story.

The aliens came from other planets from a dying star system because they heard Earth was a good place to migrate to. Or something.

If by organization you mean those who created the Gantz ball, well they exploited the fact that the aliens moved to Earth -for profit, by creating the game that is Gantz for rich people to bet on and watch for entertainment.

In reality, though, the fat retarded daughter of the owner of the organization was used as a psychic medium by a powerful alien race to send cryptic codes and mathematical equations, which served as the blueprint for the ball. In that blueprint, was the idea that a terrible alien force was on its way in the form of a countdown, an alien force that this other alien race (that sent the equations) was battling off. So they sent them the gantz equipment to defend them off. The organization used it for other reasons and then the main "politicians" or whoever, decided that they were going to have all the power when the alien force attacked, and that once they fended them off they would rebuild civilization as its leaders. Then the alien force had found ways to hack the Gantz tech, and that's why the main politicians got defeated. From there, this super alien force that sent the Gantz tech stepped in and retook over the Gantz balls, allowing humanity to win.

But, the alien force claims that humans are nothing to them, and that they are not special. They are only doing this to "restore order to the Earth." Ok. Cliché. But fine. Then we start having real problems. The super race claims that we are arrogant and that to them, we are but mere insects. Ok, fair enough. They then go on to say that we are arrogant because we think an ants life is different from that of our own. Well, isn't that exactly what you're doing now with our lives? So you're just as arrogant as we are, apparently. The only way they could get out of that would be the prove something about ants that we don't know, which would make us come to the conclusion that they are just as intelligent, powerful, and feeling as we are. Also, when George Clooney calls them out on protecting the Earth, they just say "ah, well, we didn't actually care that much, lol. We basically just flipped a coin on whether or not we should do it."

This alien force is just really inconsistent and weird, so really that was the worst part of the big reveal, though I don't mind at all that they don't care for us, just don't be philosophically inconsistent about it. Oh, wait, but that's not all. Fucking hell, it gets worse. After all that, after all that shit talking about humans being nothing but matter and electrical impulses, and how we're nothing to the universe, the aliens go on to say that 21 grams of specific data gets saved in an alternate dimension and WILL be reborn as someone else. Meaning reincarnation exists and humans DO have some relevance in the universe, since apparently "nature" saw fit to save a specific set of their data, separate from everything else to be used again. Some abstract concept unique to them. A soul. Fucking ridiculous. Not because I'm an atheist (edit: or rather, not because I don't believe in reincarnation), either, but because of the hypocrisy. Are these aliens fucking constantly drunk?