Didn't the necrons in life had mostly cancer? ALso back then it was the realm of souls before old ones touched it.
They suffered from radiation poisoning due to a sick sun of their birth system. Most never lived past a few decades. The realm of souls was beyond them and they could never match the Old One's or Eldar in power because of it. Though they were very creative and still built a sizable space empire before their decent into madness. They united against the Old One's and their creations as a way of keeping their species united and avoid civil war. It all went down hill from there.
I have a odd question. If they lived on a planet bathed by radiation. Wouldn't by most biological stand points they find a way to adapt to it?
Depends on how long their sun had been pumping out the radiation, and what type it was. If it's been occuring for a few millennia at most, then evolution may not have caught up. Plus certain types of radiation are hard to adapt to, even with genetic engineering. And then there's the fact that below a certain threshold, the radiation may have been beneficial to the Necrontyr including maximising their natural lifespan.
Indeed I was wondering if the sun had been sending out the radation since there conception. If so it must have to been a thing they had to have encountered while evolving.
So against my better judgment I saw the new Star Wars and I find it funny that all the New Order would have needed to have done to win was to have had security cameras installed in their murder fortress. An odd oversight for a tyrannical regime. Overall, it was... okay. But cynical sorcerer is not impressed.