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.

Mercenary Cloning
All Mercenaries are clones. The consciousness continues from clone to clone; memories and so on are maintained, and the Mercenary doesn't forget what they learned or how they died between missions. Nanotrasen's cloning machinery is expensive, though, and putting it on a ship that might be destroyed like the Saltshaker would be a waste, so cloning is only available between missions. These short-lived clones are also made with varying quality, which is why the same Mercenary might have vastly different capabilities between operations (and probably why Officers are paid extra for surviving). Upon completion of the Mercenary's contract, the Mercenary is cloned one last time, this time properly, and is sent out to deal with their probable PTSD. It's unknown whether the Marines bother with cloning; if they do, they clearly set intelligence priority to a minimum to keep costs reasonably low while still being strong, and if they don't then they're just ridiculously stupid.

W(H)Y are there Zurgs?
Zurganids themselves originated due to a massive medical advancement; implants that would deal with many long-term medical issues automatically. Facehugger embryos weren't actually an intended target, but they were affected just as harshly. Xenomorphs clearly could not reproduce in the way that they used to, so by some quick and extreme evolution they managed to transform into purely animated resin controlled by resin 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, some prototype Terraformers have gone rogue and stopped responding to orders, and because some of the templates had active traces of Zurganid infestation, so do the planets that they "print" onto. 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, 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 hivemind's local "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 that 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. With no hivemind to report to, the Zurganids outside the blast radius (including on the Saltshaker) die in the same way they would to the ECM countermeasure.

What are Screeches?
Screeches were originally odd little aliens discovered on one backwater planet or another; a few found their way on-board a ship landing there, and it turned out that they were actually incredibly competent with the first tool or other piece of equipment that they picked up. Mass-production began shortly after, and Screeches now see usage as raw crew numbers on ships throughout civilization. As their skillset depends entirely on what object they hyper-fixate on, Screeches can do anything from lawyering to doctoring to covert infiltration. However, their fragility and total lack of skill diversity means that they make poor soldiers; Agent Ronald is an incredibly rare exception, but even he isn't very smart.