The hexat and the fluffin are both Dunian species, brought over on Monument to serve specific purposes for the new colony. On the flora side, the same can be said of the coverleaf, poisonpole and kingseed
The hexats' role was pest control and companionship, much like cats are in real life. Which only makes sense when you consider the fact that I based them off of cats, as I'm sure you've all noticed. They began life as simply a six legged cat species, but then Isabella drew this, and their descriptor became a bit more 'spider kitty' than just 'kitty'. The picture probably shows a breed of hexat not brought over to Monument, with the Monument hexat having more mammalian limbs and having shorter fur.
The fluffin was brought over as food, their rapid reproduction and growth rates allowing a small population to quickly grow, as well as allowing rapid recovery from large losses of population in case of disease of some other disaster. They are based off of rabbits, but are much larger and don't hop quite as much.
The coverleaf can metabolise steel and atmospheric nitrogen, and provides a variety of important nutrients and minerals, with iron being the major one because I realised Aftermath should have the vegetarian option.
The poisonpole is based a bit on carrots, a bit on potatoes, and is spicy. The spiciness varies with the colour of the root, while the stem and leaves are poisonous (although fluffin can still eat them, which is one of the reasons they are there). I'm pretty sure I based the effects of the poison on something found in real life, but I apparently forgot to note down what and then forgot…
The kingseed is based on rice, but it sits inside a bunch of leaves like cauliflower. This is your grain.
The plant-animal divide occurred (on Earth) billions of years ago, but there is no guarantee an alien planet will have that same sort of divide. Similarly, carnivorous plants are a recent development (I'm pretty sure they're recent) challenging that divide. The carnivorous plants of Aftermath are therefore closer to animal in many respects, especially the likes of corals. They have an immobile adult stage, where they sit in ambush with their paralytic vines, and a mobile juvenile stage, where they fly around on five wings as tiny bugs. That's right, many of the insects in Aftermath were actually seeds! Despite several players trying to use the vines as anaesthetic, they are not good for medical use, seeing as they are incredibly painful when applied and when they begin to wear off and cause paralysis, which lasts for a few days. Neurotoxins don't make good medicine.
The carriers of the zombie fungus, the imp is a scavenger that helped clean up Monument's corpse problem, while also spreading the plague of undeath! Their design is rather simple, based on the imps from WoW, but with smaller ears and less Felfire.
Parasites, in real life, are highly specialised, especially mind-controlling ones. But in fiction, they can possess and control a wide range of alien biologies. They don't harm imps, living harmlessly within them until they die from natural causes and then possess the corpse. In humans, they activate the immune system and basically have the body attack it until it dies of exhaustion or the fungus' growth damages something important as it is spread throughout the body via the bloodstream. The fact it is an alien fungus means you have no actual defences against it!
Since you guys took your sweet time taking care of the problem, we had to evolve it into a bigger one. Fortunately, there was a highly radioactive reactor down there that we could have mutate the fungus horribly until you got the highly advanced Alpha Zombies, because we all know that's how radiation works!
After having already designed the Earth Serpent and the Sky Serpent meme having been banging on the walls of Aftermath's metaphysics, I decided it would be funny to have giant serpents for each of the four aspects of Nature. The Earth Serpent showed up right at the beginning, before this idea even existed, but fortunately it appeared in the Earth direction of South-East, so the serpent idea was a go. The Sea Serpent appeared next, but was not really investigated either. Of course the Sky serpent was the one everyone cared about, having flown in and used the radio tower as a nest. The Sky Serpents live for centuries, and the babies will be toddlers by the time the last of the playerbase dies of natural causes. Long live Serpenty!
Based primarily off of pterasaurs and dragons, these guys basically replaced birds, with flyscence being a specific species that lived in the city and annoyed people (think an unholy amalgamation of pigeon, crow and seagull) and wyvern being a more generic descriptor.
After you guys decided to tortoise somebody, I just had to do this. Unfortunately, the torture never showed up, but its design has been around for a while. It was another animal with plant symbionts, a giant tortoise with bushes growing on its shell (think the Pokemon Grotle) and turrets sticking out of the sides, ready to use Stun Spore, Sleep Powder or Poison Powder.
Surprise! These guys don't actually return your memories, instead playing with what you do remember (be it lingering memories or actual memories) and your imagination to create vivid hallucinations. I'll admit occasionally it did take inspiration from lost memories (someone had a hallucination of falling over as a toddler) but primarily it was based off of a line from the Book, about Nature stealing everyone's memories with vines.
The Mafia had an operation spiking the river with the juice to get people addicted, and then culling all the plants to gain a monopoly. Oh, and Noneapple almost died overdosing on the stuff in Session 2.
NOT A DRUG!!!!
Ahem, now that we have that out of the way, sweetscent was designed because I wanted flowers in Monument. That's it. They smell nice and have a calming scent not unlike incense, but are not hallucinogenic or narcotic or mind-altering in any way. They make for very sweet tea, though.
They came in four varieties: a purple disinfectant, a poisonous red, an analgesic blue (with overdose causing hallucinations) and a boring lilac that tastes terrible. Mostly there because we wanted an early game hit to colourblindness before the Heizar.