They were, they are, and they yet shall be. Ancient--no, timeless--beyond any record of human awareness, memory, or history. Research across different planets have revealed logs that call them different things: the Sshugursh, the Shabbt'bomaal, the Scoh'tarren, the Stho-zhoma, the See Blinders, the Sight that Preys Eternal, and more. For ease of reference, we refer to them as one thing: The Speculators.
We have no first-hand data from them. We have barely anything on them at all. The only reason we know of them is because of our interplanetary teleportation experiments, our scientists finding a few logs in some long-abandoned libraries. Panicked, terrified, speaking of invaders infiltrating their planet and nothing able to stop them, picking them apart bit by bit. Then, assumedly, moving on when leaving the planet an empty husk with nothing more.
We can't even possibly begin to describe how many promising scientific sites we've found in new planets, only to find all of the logs end in terror of these beasts. We can only guess that so many of the planets we've never found any sign of life on were wiped clean as well.

What we can gather of the Speculators is very little, fragmented across different logs and different databanks--they appear to be an ever-growing and adaptive psionic hivemind race interested in consuming planet after planet in an ever-increasing swathe of eternal conquest.
They find a prospective planet and pry at it from the sky, tweaking with the atmosphere in subtle ways; they introduce diseases, upset the ecosystem, shift the heat of the planet. And then, when it is sufficiently weakened and chaotic, then they invade. They send a small batch of soldiers, looking for members of the planet's species--and then start corrupting them to become as them. They take their minds, all of their memories and thoughts being sent up to the hivemind for dissection, while the body becomes one of their soldiers.
The differences are subtle at first--a constant smile, pale skin, stilted speech patterns, but as their body morphs they lose their face and all identifications of gender, their body becoming less human and more...humanoid. Their psionic power amplifies dramatically, as does their strength, and before too long the corruption turns them from a man to a ferocious killing machine. But even before the corruption becomes obvious, they are already a soldier for them, ready to continue furthering the Speculators. All it takes is one single compromised body to doom an entire planet...and even if their initial squad fails, they can send another.

You might wonder why I'm writing about this now. Why I'm hurriedly updating all of these files.
We've been dealing with a rise of new diseases as of late. We've been dealing with global warming as well. And for a decade, none of us saw this as a big deal.
While heading to work today, though, I saw one of them. A lanky, pale man--his face frozen in a smile. And I think he saw me, too.
They're here.
And we're next.
God help us.





Former Human: Smiling Civilian (Wields a pistol and takes wild potshots. Shoots 12 times before needing to reload.)
Former Sergeant: Smiling Officer (Wields an SMG and fires in short three-round bursts. Shoots 25 rounds before needing to reload.)
Former Commando: Smiling Soldier (Wields an assault rifle with an extended magazine. Shoots 40 times before needing to reload)
Imp: Faceless [Soldier] (As the name suggests, a faceless humanoid mass. Their psychic powers are weak, but they exist, and can rend a normal man into a gibbering braindead mess with just a few shots. Their claws are also nothing to laugh at either, with a nasty and fast lunge that can take most warriors off-guard)
Demon: Mindless [Soldier] (Significantly less humanoid, the Mindless is primarily muscle and no brain, simply slithering forward and tearing and biting into any enemy in its way. They lack psychic attacks entirely, but make up for it with carnivorous hunger and blinding speed)
Spectre: Soulless [Soldier] (The Soulless are empty shells of what once was, a mad conglameration of thoughts, emotions, and various other ills held together in a weak psychic body. They roam around, mad, only identifiable by little whisps of white smoke and a constant whispering in their location--whenever they come across anything that isn't a Speculator, they attack in a blind fury, digging into the poor victim's mind and starting to suck whatever they can from them)
Lost Soul: Flying Eye [Searcher]
Cacodemon: Eyemind [Searcher]
Pain Elemental: Greater Eyemind [Searcher]
Hell Knight: Philosopher [Scholar]
Baron of Hell: Greater Philosopher [Scholar]
Archvile: Spokesman [Scholar]

Revenant: Sniper Soldier [Soldier]
Mancubus: Siege Soldier [Soldier]
Arachnotron: Suppression Soldier [Soldier]

Spider Mastermind: Supreme Commander [Superior] (A thin, tall figure that does nothing except stand there. Whenever he looks at someone within range, their view darkens, static occaisionally runs across their screen, and they start taking damage repeatedly. Does not move--whenever he enters his pain state, he does a lot of AAAAAAAAAAAAAAA 0 A_Wander so as to appear to teleport. Whenever an enemy goes out of LoS or range, he does an A_ClearTarget)
Cyberdemon: Cosmic Horror [Superior]

SS Nazi: Grey