The red sky (IMHO) is only a scenographic effect (it reminds me of "Gilgamesh" in some way), I would like to have it explained on the plain of science and not eschatology. If the sky turned red because it's doomsday so Oku is going down the hill of the "deus ex machina" explanation of what is happening, that's the same to say that he doesn't know where to go and needs a shortcut to avoid deep thinking (if someone watched the ending of "Battlestar Galactica" , sure knows the feeling...)I disagree on some points.
The dreadnought to me seemed to be doing the job of getting the "stage" ready, in other words, turning the sky red.
The way Oku went through "Phase 2" is erratic: In the first phase the game was something that no one else could see, the material damage was somehow limited (I mean what normal people could see fo the battles), the game was more fascinating, because it was something that could really happen around us.
When it turned the game in something bigger, that people could see, he run in the field of the alternate reality, but doing it , he never considered the implications of the actions of the battle in the world and kept the level in the way that the actions presented in the manga were not changing the normal flow of time: even if we're in the disciplined Japan, it's incredible that there is no a "state of emergency" or martial laws in act... People goes to school, at work, like nothing has happened... With the scale of destruction in Japan and in Italy (and we don't know what happened in the other countries) the Americans would be on Defcon 2 or Defcon 1. If it's stated that now we're after 9/11, they are just a little reactive on attacks and awaking in the morning with a red sky would mean that we should have seen more planes coming from the continental USA and before the Japs could have said "America is over" a couple of good Hydrogen bombs exploding even if ineffective against the target, those F14 should have carried tactical atomic missiles too. but it can be questionable.
In my opinion is both for the usual effect of an attack on New York and for the (still usual) humiliation on the USA that appears on many old anime for later showing Japan saving the situation. Same think happened in the battle of Rome. I was expecting some good unknown team to save the day, even the Switzerland team, but it looked like only the intervention of the Tokio team changed the situation...Then the attack on America should be for psychological effect; imo it's pretty clear by now that it's not a matter of power, but a matter of fun, simply because Gantz technology has proved unbeatable (the soldiers fall, they could make others, an army of clones, or whatever, or just teleport the aliens to nothingness).
It is not a wrong assertion, it can be simply desumed by the way they were disguised, I mean the big ones... I can't figure how they could, for example exchange themselves with the statues in the Trevi fountain (ok, maybe some thousands monkeys did the job at night...) if not with teleport or something more sofisticated then teleport (they actually seems interphasic), in any case, they seems beyond the space travels using space ships, if they have not teleport, they have interphasic technology that is even more sophisticated.Now, you saying the aliens can teleport is a wrong assertion, we haven't seen to this day an alien using teleportation technology, HS and KB excluded because they were being manipulated by Gantz.
As i said, I think we won't get accetable answers to these questionsAlso, about who's behind Gantz receiving orders from space, that isn't clear either; we know that the y-gun suposedly teleports the "aliens" to somewhere up above, but whether it's a satelyte, a spaceship, another planet or some other thing is unknow, and it's also unknown whether what lies in that place is the origin, since it could very well be just another creation and the source could be on Earth.
What I mean with what I wrote is that it clearly looks to me that Oku plaid a game bigger than his possibilities:As for the timeline, now you've got me, but I know there's info on it on the Manual and also a remark about it in one of the chapters after Kurono's ressurected, if I'm not mistaken.
I know that at least a year has gone by since then. Suposedly Katou was ressurected six months after the budha mission, and the Nuri mission should've been only a few days after the Oni mission, but I'm not sure and I'm too lazy to check the raw of Kurono's ressurection for the any time remarks...
-If he begins in 2000 it HAS to keep the storyline running in 2000/2001, while the last chapters are clearly staged one year ago: for lazyness, lacking funding or whatever he used pictures from googlemaps, showing the Rome of the last year, confusing. I can't say more on the other cities or the Japan stages, in any case the timeline is not consistent. Actually I was happier to see real stages even if in the wrong timeline, while in the last chapters he began to disguise things, showing things that does not exist, like the American carrier (the CVN 89 does not exist) and the plane that crashed in Berlin (I found what is the original plane, will show at the bottom of the page )
-When he went on "alternate reality mode" showing the battle in the real world he should show more of this alternate world, how thing could change in our world if the Gantz thing existed for real, something like Japan government thinking of an attack from North Korea or Russia and reacting in conseguence ("Watchmen" would be a good reading...)
-As you also said, a lor of subplots that he didn't expand
It's because of it that I said that I would have preferred a linear and simpler story, I'm beginning to like the ending of the anime...
It's very late here, in any case, the plane crashing in chapter 302 is a (badly) disguised version of a 747-446 (or 747-400D) of the Japan Air Lines (Jal) code ja8073 (with the old paint) here are some shots: