Lore Tidbits

MercDonalds Background
When humanity began to spread into deep space fast food groups ended up being heavily involved in supplying food to various exosolar locations. Due to near constant corporate fighting and piracy they found it really really hard to actually keep a reliable supply chain running. A certain burger joint went "Hey this whole franchise thing worked well with food, why not try it with mercenaries so we have a military to protect our trade routes." It worked well enough that the company switched its primary focus from food to mercs and later changed its name.

Joining is simple and provides a host of benefits. Individuals get pointed at crews who are hiring while new commanders and already established groups gain easy access to military equipment, personnel, and jobs. Interested parties just need to meet some minimum requirements and follow some basic rules to join up.

Do you have/need a ship? Crew? Willing to shoot at things we point you at while not shooting our stuff? Good. Welcome to MercDonalds, the supply and intelligence departments will contact you shortly.

Mercs are clones
All mercenaries are clones. The original copies sold their identities and skills to Mercdonald's, and the clones live on in that form. The clones will continue being made with that identity even after the original dies. Clones are aware of what each iteration of clone is doing, while the original isn't aware at all. Essentially, each clone is in itself a hivemind, always kinda aware of each other and sharing memories, hence why you would know what happened in the past, even if you died. Head positions are semi-clones. They're dedicated to Mercdonalds and don't have an original, they just get cloned when they die.

W(H)Y are there Zurgs?
Zurganids themselves originated due to a massive medical advancement; automatic implants that would destroy any Facehugger embryo in the implanted, among other features (like negating drug overdoses.) Xenomorphs clearly could not reproduce in this way, so by some luck they transformed into animated Xenomorph resin controlled by cores, which are the only remotely "organic" thing inside of the Zurganids. This also lets them reform upon death, but resin isn't as resilient or powerful as the exoskeleton and muscle that Xenomorphs used to have.

As to why they are on planets in the first place; W(H)Y wanted to mass-terraform planets in order to maximize profits; to this end, they created massive Terraformer ships that would reshape planets to be more or less habitable, and create installations in those planets that would be identical regardless of the original planet's composition. However, for one reason or another, some of these Terraformers have gone rogue, and they plant Zurganid resin in the planets that they terraform. Ideally, W(H)Y would shut them down or destroy them, but because they are so fast-working they rarely give enough of a warning until after the fact, and by the time MercDonalds (or any other group) can respond the Terraformer is back in the Warp, so all the responders can do is try to kill the hive so that the planet (minus the section they nuked) can be put to use. It's also worth noting that a large part of the planet is infested; there are far more than the fifteen or so Zurganids that the Mercenaries fight.

What actually Exterminates the Zurgs?
The Cores, Ronald's report, and the Artifacts left behind on the planet all share something in common; they give a better idea of what the Zurganid Hive's "frequency" is. After getting a precise reading from enough intel, the Saltshaker can then prepare the Extermination, which involves a two-part attack. The first part is some kind of ECM pulse that shuts off the Zurganid hivemind for a few seconds, which has the side effect of stunning any Zurganids in range, though this hardly matters. This is effectively a supercharged version of the ECM ship order. The second part is a high-yield nuclear warhead dropped directly on the core of the Zurganid's planetside hive network. Without the pulse, the hive would be severely damaged, but the parts not destroyed could pick up the slack, and the hivemind would continue to live. However, shutting off the hivemind prevents it from adapting to the damage, so it is totally destroyed, and so are all of the Zurganids on the planet. With no hivemind to report to, the Zurganids on the Saltshaker die in the same way they would with the ECM countermeasure active.