Does it get harder based on population? Nishi letting others die meant easy missions
Nishi has been playing the game a long time, but never apparently gotten a hundred points yet, otherwise he would've gotten a better weapon. He loves the game and wouldn't leave it, nor would he care enough to bring anyone else back. Or maybe there was someone once, who then jilted him, turning him so cold and bitter to the world around him.
After the Onion Alien mission, he states its the first time in a long time that ANYONE has survived a mission other than him. He then gets a medium mission instead of the usual easy one.
His point count would be much higher if he actually had a lot of missions like that one, or harder. So, I'm thinking, he just kept doing a lot of easy ones.
And after the second mission, they had even more people left alive, so the next one was a harder one.
Are the missions prepared in advance, less there be a sudden alien strike against humans such as the Countrymen aliens and the Osaka battle?
If so, then why the long delay between some missions, while others were just days apart? Does it take that long to find one of appropriate skill level? Does Gantz have other teams somewhere else? In the Anime he would just appear in the apartment before the missions. Can each Gantz's sphere be in various places at different times? Or do they remain in their city, monitoring it constantly, for any signs of aliens?