D&D 5E Making technology eldritch

[TheIdeaOfGood]

Check out Monte Cook's Chaositech and the more recent Arcana of the Ancients.

Exactly what you are looking for.

Frick! I actually own those...I have so many PDFs that I am losing track....thanks, guys!

 

[TheIdeaOfGood]

That fits with the OP. The nanotech could be turning people into clowns.

I know it's because of my typo but the idea is not half bad...and not just because it reminds me of Killer Klowns from Outer Space, which I love for its cheesiness...

But some sort of creature similar to a clown with a chillingly cheerful demeanor and " tricks" that are actually deadly traps. " The Star-Court's Jester".

 

[BlivetWidget]

I think you should take a look at the novel Roadside Picnic. Basically, there is a brief alien visitation that leaves behind an inexplicable array of what we have to assume is alien trash. I think this fits in well with your idea of sci-fi so not-understood that it's fantasy. The following quote paints an analogy of the aliens as picnickers and humans as the animal inhabitants:

A picnic. Picture a forest, a country road, a meadow. Cars drive off the country road into the meadow, a group of young people get out carrying bottles, baskets of food, transistor radios, and cameras. They light fires, pitch tents, turn on the music. In the morning they leave. The animals, birds, and insects that watched in horror through the long night creep out from their hiding places. And what do they see? Old spark plugs and old filters strewn around... Rags, burnt-out bulbs, and a monkey wrench left behind... And of course, the usual mess—apple cores, candy wrappers, charred remains of the campfire, cans, bottles, somebody’s handkerchief, somebody’s penknife, torn newspapers, coins, faded flowers picked in another meadow.

This alien trash, from the point of view of humans, is a collection of wondrous, bizarre, often deadly artifacts. If you don't have the time to read through the novel, this site has a nice summary of these strange effects and artifacts.

 

[Laurefindel]

Going along the « sufficiently advanced science is indistinguishable from magic » route, you could have a selection of « naturally » occurring spells. Random sleet storms. Dangerous killcloud fog. Random « waves » of dispel magic. Etc.

 

[Samloyal23]

Nanites multiply and get in everything, like sand. Some invade your brain and upload a mental virus that changes your personality, turning you into a savage killing machine. Other nanites connect your mind to other hosts, create a hivemind. Another type of nanite is like a tiny projector, get enough of them in an area they can create "holo-matter" terrains and illusory creatures. Beneficial nanites can repair your body, allowing you to regenerate, but when those go wrong they can change you unpredictable ways...

 

[Shadowdweller]

Something else that seems like it might be setting-appropriate:

The Patchwork Man

A chirurgeon of superlative, even futuristic or otherworldly, skill, the Patchwork Man has extended his life for centuries by replacing parts of his body that grow old or wear out. (He probably knows some advanced bioalchemical process to restore brain function). The Patchwork Man has accomplished this by stealing organs from healthy, young specimens; probably using some sort of supercharged chloroform to subdue them. The Patchwork Man might have augmented physical abilities as a result of using organs from the strongest, healthiest, and/or most agile victims. He might also have an army of flesh-golem like minions or even an assortment of monsters put together from pieces of creatures that were never meant to be joined or rearranged into such disturbing but effective shapes. The Patchwork Man is forced to stay close to society to scout out and secure the very best organs; but must hide his features because of the grotesque scars and sutures that cover his body. He may or may not leave some victims alive with only an arm, eye, leg, or something else taken.