A short summary of the scythod as I know them. Please point out any and all mistakes and I will fix them. Spoilered for being a wall-o-text.
On the Scythod.
Many new and strange creatures arrived in the land of Everoc after the founding of Spearbreakers. Some of these were overtly hostile from the start, while others preferred to stay neutral. Some even befriended the natives of Everoc and have become if not common, more prevalent in cities and towns. Most scythod fit into the first category, and are outright hostile. Some individual scythod have been shown to communicate an even coexist with other races, but these are the exception to the rule. This chapter of Urist's Handbook for Foolhardy Adventurers will cover what is currently know about the scythod into one convenient place, to reduce your chances of becoming mincemeat.
Origin: The scythod are originally from a planet called Piscyth. Piscyth orbits a brown dwarf star, which is much smaller and colder than our yellow dwarf, this meant that the scythod could not rely on heat or light to see by. The scythod were taken from their planet by both Parasol and Ballpoint, to serve as shock troops. The scythod on Everoc are a mix of soldiers and free scythod. The free scythod have organized into tribes and communities, often in mountains and other regions inaccessible by land or sea.
Biology: A scythod resembles a preying mantis to an extent. They stand at about two dwarves tall, or close to ten feet or a little over three meters. Scythod don't have a "head" instead their necks terminate in a set of three dentaries. They have four triple jointed legs, tipped with spikes rather than feet or hooves. All three leg joints bend in the same direction. They also have two triple jointed sets of arms. One set ends in a meter long scythe past the second elbow. The second elbow also actuates in the opposite direction, resulting in a scythe that points towards the ground. A scythod's second set of arms terminates in a set of three opposable claws. The claw tips are ill suited for tool use, but are sharp enough to preform any task accomplished with a knife. The joints on this pair of arms appear to have a much greater range of motion than those on the other, approaching 180* of motion per joint. Scythod are covered in thick, segmented chitin. The chitin is thickest on the neck and around the brain-case. It is thinnest around the joints, to allow free movement. Scythod chitin is also the scythod's main sensory organ. The chitin detects subtle vibrations and changes in temperature, this allows the scythod to form a picture of the environment. Scythod chitin is sturdy, withstanding temperatures of several hundred degrees Fahrenheit, with a material strength comparable to bronze. This strength is necessary, as scythod chitin can be very susceptible to pain.
Society: The original scythod society was in a constant struggle for food and as such scythod now tend to value honor and courage in combat. Scythod find it perfectly acceptable to consume any of their kills, and make no distinction between sapient and not. Scythod society on Everoc is organized into clans, each with its own leaders and domain. Scythod place great emphasis on loyalty and familial ties. Disputes are settled with a trial of combat often to the death.
Scythod are not inherently hostile, although many share a cultural hatred of dwarves and humans, by reason of the fact that Ballpoint took them from their homes and forced them to work pretty much as slaves, as they put little to no value on Ballpoint's money. Their hostility primarily stems from how it was practically forced upon them on their homeworld of Piscyth. If you were a wuss and didn't fight, you got killed or starved to death.
Ballpoint is the only timewar company that abducted scythods. Parasol is mainly dwarven (with humans in lesser positions), and they don't think much of other races. I'd go as far as to say they're a bit snobbish about it.
I'm not sure where you're getting the scythe pointing towards the ground... They have two scythes, and are somewhat dextrous with them - but overall, the scythes are primarily just weapons, and rather clunky when it comes to detailed work.
I
think I loosely modeled their chitin after copper and some other metal/stone, I think - can't remember which.
You forgot that their society puts a huge emphasis on it being honorable to be eaten by your own kind. It stems from their predatory nature, the scarcity of food, and how they weren't apex predators at the top of their food chain on Piscyth. If a scythod died and was eaten by another species, especially one that was stronger, the meat from that scythod was potentially forever lost. Not being eaten meant you weren't good enough even for the starving to feed on you, and was basically the greatest insult possible, particularly to living kin. Thus, it was honorable to be eaten, and more so by your own kind. Not only that, but scythods absolutely detest wasting food - it's more or less part of who they are, in the same way that some terrestrial species gorge themselves on whatever they can.
Everything else looks just about right! I'm impressed. I'd forgotten some of that myself.
@Talvieno part of the problem with the radiation mod is that it's effects are inherently random. In game evil weather doesn't have a status marker or change the dwarf's name, but there is usually only one effect per biome, whereas the radiation can have many effects. If possible, a good fix would be to include a visual cue in the environment that there is radiation. Dead grass or trees could indicate radiation, rather than a tag or graphic. You would have to check your dwarves for the specific symptoms but you have to do that anyway.
Also, good work on the railgun. Comments: The stock looks a little to round to me. Also I think it would be cooler if the barrel looked different. The extra barrel is unnecessary as there is no propellant in a railgun. Any space not spent accelerating is time spent slowing down. The magnetic coils and/or rails should probably go to the end of the gun.
First part: Can't be done. Radiation zones don't have their own biome - they're randomly plopped into savage wilderness with either a 25% or 50% chance of being placed. If you kill the grass for one zone, you kill it for all savage areas, making that useless as a telltale sign. You see my dilemma here. =P
Second part - Hmmmmm... Yeah, you're right, it doesn't need the extra barrel, although the flash hider could still be useful - particularly because railgun slugs have been known, in real life, to ignite the air around them as they leave the barrel.
I could fix the stock, but a lot of it is just solely based on Splint's original design.