I found these old Necromorphs sprites

And i desided to improve the idea

a little bit...
Im still working on it but i have the basic idea,i can drop .dmi soon if you guys want.
Basic idea for event\gamemode is that Necromorph is a space virus (that was probably created by syndicate and it broke out) so there is no marker thingy and necromorphs have evolution and stuff.
So i didn't really rely on the lore i just threw it out the window in order to make it more interesting.
Basically round starts with 1-4 Slashers,they need to farm some dead bodies.Each necromorph can plant only 1 corruption node for his entire life and it will spread until the node is broken.It heals necromorphs and in some time it will start to release poisonous gas.Some Slashers HAVE to evolve into an infector in order to make new "members" but if the body is laying on the corruption for too long it will be infected too but it takes much much longer.Cyst will randomly appear on the corruption and will serve as mines.So corruption nodes have 3 ways of defending it self.Gas,Cyst and Necromorphs.
In order to evolve Necromorphs have to wait to gain biomass or too chew on corpses (grab and click on self) this can also be done on living mobs this will cause a lot of brute damage.Every t2 is a much much stronger version.Necros can only evolve on the corruption.Slashers have 4 evolution paths.
Leapers are basically flank\sudden attackers who can leap onto enemies and disable them really quickly.
Infectors who can quickly create Necromophs it takes 5 minutes on a dead one and 1 minute on a alive host.So Slasher has to tackle a host and then infector can grab onto it (takes 10 seconds) when it grabs the host it can safely infect it without it escaping.
Spitters who are well.....made for spitting.
Infectors also can infect certain body parts.Like arms and legs.Arms and legs will just serve as mobs who will attack everything (exept necros of course) on sight but head can be controlled by a human.Its called a Creeper its a key to victory.Creeper has to find a corpse in order to turn into a Shambler.It will just take off the hosts head and replace it.Then comes a shambler.Shamblers powerfull zombies,walking corpses of who once were marines is now used as exoskeleton for Creeper.Its basically just a zombie,because of muscle memory shambler still can use some wepons like knifes,pistols,rifles,m39,but it can't use complicated items.After some time Shambler turns into a Fodder.Fodder can use complicated items like Axes,Crowbars,blowtorches,etc.But it doesnt know how to use them properly thats why it can hurt is self alot in the process or the process will take a shit ton of time.It can also hold guns and shoot them and even reload them but of course it does it slow..Shambler has more physical strenght as it evolves further it loses it,if Shambler or Fodder dies hovewer Creeper will just detach but in order to make some time for a creeper to escape body will detach into a still functional legs with 3 sharp tentacles and 2 arms with razor sharp nails and tentacles.Fodder T2 is more interesting,it can do everything that a human can do exept for speaking properly.So if you wear a mask and a helmet you can fool humans and murder them.Fodders T2 in order to be more like human lost they're Necromorph powers (so it means no vent crawling for ya and extra damage) thats why you can count it as the weakest necrmoroph on the team but the most usefull.But Fodder T2 still gains biomass because of its special ability.If T2 Fodders biomass is maxed out it can mutate it self into abomination(not predalien) this thing is strong can put down 1 or 2 if its skilled marines but fire is its best weakness.It can also infect alive hosts(and only alive hosts) but it drains its whole plasma + it cant move and its very vanurable while its filling paralyzed host with infection but if it wasnt interupted unlucky victim will turn into Fodder T2(it 5-10 min of course) altought its a Necromorph still it cant use vents there is no return point after turning into abomination.So Fodder T2 really should only use this ability if they're indetity has been revealed or if they're sure that its gonna be really usefull.
Infectors can also infect Monkeys in that case it will turn into a Lurker,its a range class like spitter but it does less damage for exchange to shoot 3 spikes (you can shoot 3 spikes at 1 target or shoot 3 at once so that there would be 3 spikes at 3 tiles( i hope i explained it right))
There can be only 1 Necromorph that can evolve into last tier because last tiers are very powerfull.
Spitters dont have they're last tier(for now) and Fodders too so they doesnt count.
Leapers evolve into Tripods
Hunters into Regenerators
Lurkers into Tormentors
Tripods are big 3 legged creatures they can do a death leap that will tackle and deal damage to a human(depends on an intent but it will still tackle for a long time).It can also infect like an infector but i has 2 modes.1 one is a quick infect in that mode it will infect a host in one go (takes 5 seconds) but it will kill the host in the process the second mode takes longer but it wont kill the host in the process.

Regenerators are big creatures that are able to regenerate outside the corruption fast and can deal insane amount of damage.Its almost impossible to kill it but you can kill it much faster by lighting it on fire.

And finnaly Tormentors ,these HUGE creatures are the biggest ones out there,they are able to break walls like xenomorph crushers shoot a lot of spikes and deal a shit ton of damage

I think i told everything that was on my mind tho im still working on the sprites and whole idea in general i would be happy to create this but im still learning SS13 code so i dont think this idea will see the light of day soon.