Finished the book and am looking forward to running the EVAC scenario. It has me thinking about variant Xenomorph lifecycles and representation within the game system. I said the following on the unofficial Discord and am reposting here to see if I can get any further discussion going. Spoilers ahead for Inferno's Fall, EVAC, Destroyer of Worlds, Colonial Marines Operation Manual/Frontier War, and Alien: Cold Forge and Alien: Into Charybdis:
My interpretation of Inferno's Fall is that the Xenos created by the black goo bombing are closer to Neomorphs (with the Eitr in the ecosystem causing the red tinge which overpowers the corpse white coloring we saw in Covenant) as opposed to Baseline Xenomorph XX121. There are references in the text to secondary jaws, but those could be Neomorph style "goblin shark" jaws. The Inferno's Fall bombing has notable differences from other black goo bombings:
1. This black goo bombing seems to cause creation of Neomorph, not spore related incubation within victims as we see in Covenant, nor Anathema transformation as we see in DoW and CMOM.
2. These Xenos are described as more heavily armored than the Jackals are used to dealing with (notably by Mae during the holding perimeter action in the final act). Neomorphs generally appear less armored than typical XX121 and the RPG stats support that. This extra armor could be a consequence of a. the base wildlife as the native lifeforms are described as having armored crests etc. and this could be a the black goo merely expanding or otherwise enhancing that feature, b. again related to Eitr contamination as we see descriptions of the durable nature of Eitr (the Giger Xeno Crucifix mural found in the Engineer Ruins) and the armor is a result of additional Eitr in the wildlife's bodies being positioned as armor by the black goo mutagen properties, or c. this variant of the black goo creates more hardy Xenos?
3. In EVAC we get description of the direct transformation of the scientist Alexi into a creature represented with Stalker Xenomorph stats (aka the Praetomorph from Covenant). This I'm willing to view as a game mechanic representation of the armored red Neomorph style creature, though this being a hint of the relationship between David's Stalker/Praetomorph and the Shanmen creatures is also worth considering. We have similar precedent from Fallout of an Imp Xenomorph stats being used to represent a rat birthed Xeno and there is no indication of a David connection there, so I think the "armored Neomorph" option seems more likely to be author's intent.
4a. The black goo found in the Engineer Ruins (a different source than the bomber released black goo) seems to cause the exposed Engineers to transform into Black Xenomorphs that more strongly resemble the XX121 variant. These two Engineer derived Xenos are hostile towards the bombing derived red Xenos, possibly because they are a. derived from different black goo sources, or b. because they are not Eitr infused like the native creatures which otherwise are not shown to attack each other. Either way, this is likely an homage to the Black vs. Red Xeno XX121 hive conflict from the old Dark Horse Comic Aliens: Genocide. This seems to me to be strong evidence for multiple strains of black goo in the story.
4b. Conversely, the Engineer Ruins black goo causes the archaeologist Antonijevic to become a pale monster with black eyes more consistent with the Holloway Anathema and the Anathemas seen in DoW/CMOM. No red tinge mentioned but how much of that is attributable to the victim not being contaminated with Eitr, the black goo not being the bombing black goo, or the creature just not being alive long enough to go completely black Xeno Bodyburster?
Regardless, I think this book provides inspiration for two exciting new monster pathways to catch experienced Alien RPG players and scientist characters by surprise. I truly believe unpredictability adds to the horror:
1. Black goo on another Eitr heavy planet leads to direct transformation into Stalker stat blocks described as armored looking red Neomorphs.
2. Ruins black goo that follows a pathway of Anathema to Bodyburster (instead of Stage IV disintegration) without the need for Chestburster and 26 Draconis inoculation as we saw in DoW.
Am I missing any other key examples from the book? What was your interpretation on reading? Neos, Xenos, something in between, multiple black goos, something else? Would you try any of these new "lifecycles" with your group?