What Happened to Nerud?

[yuzhonglu]

They tried jumping into a blackhole. Got that part.

So why are there weird zombies and infestations everywhere?

[Jeff]

To keep the player occupied with stuff to shoot while on the way to objectives.

[dr46onfusion]

They kept themselves in a pod when they jumped into the blackhole, it did something and screwed with their sentience so they became creatures.

Maybe Tal'ratha tampered with their machines since he wanted to preserve his planet, hence assimilated them?

Thus all that's left is walking husks.

[Cutlass Jack]

The Geth turned them into husks.

[adobo]

Everyone died and some kind of infestation ran free without anyone to clean it up. They have a "purge protocol" so it's a recurring problem that needs something in the system already to deal with it.

[Sheogorath]

From audio logs and various books, there was some division with those who wanted to jump through the black hole, and those that didn't so most went into the pods, though there were 2 seekers and a few others that did not, and sealed themselves off, it is implied that the dude you meet was created and is a construct not one of the actual people, and did not agree with the jump, not sure why though, and since everyone in the pods became mindless zombie like creatures, and those who stayed and sealed themselves in various places died hence the many corpses, something clearly went wrong unsure what exactly though.

[A Helpless Baby]

The lack of an explanation on that is kind of annoying tbh. you get lore saying that they went into the black hole for a while but when they came back out they found that time had moved slower inside and that the rest of the universe had undergone heat death. It doesn't really state what happened from there.

it's pretty weird that you find corpses curled up in the fetal position or sitting with their hands on their head like they died some long and slow way but none of the audio logs they have seem to be recent enough to indicate something has gone wrong.

I think the 2nd story line with the big fat guy as a boss implies that the shielding on the stasis pods wasn't enough and only those in the special deep vaults survived.