1984
Grimdark has always been a concept of humanity living in the worst environment as possible, and there is not even a single joy can be found in grimdark. 1984 is such example of grimdark. It is a novel by George Orwell published in 1949. It is primary about what happen if the government has the complete control of everyone, where you will be watched everyday and being forced to do what the government said, or else you'll be tortured and mind-raped to absolute despair. This book is basically the inspiration to all grimdark totalitarian dictatorships, including Paranoia and warhammer 40k.
Plot
A member who works for the Ministry of Truth name Winston wasn't happy about his life. He is sick of doing the same thing, exhausting at work and not having enough to eat. But his life changed when he met Julia, who gives him what he want, which is something the party is unacceptable with. Winston had a fun time fucking Julia, learning about the past and eating the real food from the party, until he did not expect the Thought Police spying in their private sex room and was sent to brainwashed. O'brien, who was Winston's boss, is actually an agent from the party. He tortured Winston, then sent him to room 101 to meet his fear. In the end, Winston returned to normal and believes 2+2=5.
few grimdark elements that the warhammer 40k inspired from 1984
-The Big Brother: Big Brother is basically a non-existent figure head created by the fellow jews for those poor bastards to worship. Like many religions, gods are non-existent bullshit that were created to waste your time in.BLAM!! HERESY!!! except the Emperor.
-Constant Surveillance: In 1984, there are these shitty TV's that were created to stalk you and troll you everyday call the "telescreen". You cannot turning in off, and even if you do turning it off, you will be capture by thought police and getting your ass beaten. There are other surveillance like helicopters (for tall apartment building), thought polices, and even your own children (damn government bribed them with candy). The only people who are free from this nightmare are the underclass Proles, and that's because they're so dumb the Party considers them animals who do not give a fuck about politics, doing nothing but work and wank to porn. Yes, you yourself are one such filthy dumbass Prole, using this Telescreen for hentai instead of actually doing something. In Warhammer 40k, there are the secret police of the Inquisition which have psykers reading people's mind everyday, and Adeptus Arbites who serve fair justice to common proletarians everyday.
-Warfare: In 1984, eternal war is the best way for Oceania to have their lonely excuse for fun and boost their Jew golds; they wage unnecessary wars with friendly countries just so they can spent most of their money on building more flying metal boxes, instead of giving benefits to their own people who are cramped into 1000 meters high city prison for your grandmother to live in.