I would take a page from Paranoia the RPG.
A little bit of knowledge is a dangerous thing, and just like Friend Computer in Paranoia, the upper crust of the AdMec has no real concept of the human condition. The human machine, definitely, but not living, breathing human beings.
There's plenty of drugs in circulation. Human abilities can be enhanced in various ways through specific drugs, and the AdMec tries, in their blundering way, to exploit this to its fullest.
Manufactorum workers work 24 hour shifts and are on massive doses of stimulants, making them careless and prone to fits of rage. Of course the AdMec only understands that they get more consecutive hours per worker when the workers are drugged to the gills. Side effects? What's that?
Children are high on smart drugs during school hours. The rest of the time they're either working or stoned placid. Which of course means that a large percentage go through brutal withdrawal up to several times per day, unless they or their parents can get them what they need on the thriving black market.
Speaking of markets, and recreational areas in general, these are explosions of colour, weird geometric shapes, and all manner of weird smells. Shoppers are expected to drop a few trips to enhance their shopping experience and decrease their expectancy of the goods they buy.
Everyone is excessively polite, even while they're murdering you in a blind, drug-fuelled rage. The AdMec have concluded that politeness decreases friction in the human population, so any lapse in manners is grounds for being turned into a Servitor. People either learn early, or become Cherubs.
Barring worse fates, it is standard practice to turn parental units into servo skulls for the children, once these mature to a certain age. The Servo Skulls maintain much of their practical work experience, and serve as a combination of training wheels and surveillance units for the children. The Servitors do, of course, not maintain any semblance of humanity.
One of the most popular - and secret - cults, is the Cult of Ecologic. These people secretly harbour things like malnourished plants, dangerous, if diminutive, wildlife, and similar, and worship The Emperor as a kind of nature god. Of course, none of them have ever actually seen anything like a natural ecosystem, so they have some pretty damn strange ideas of what exactly it is. And a lot of vicious in-fighting is centred on arguments about this.
The deeper levels of the Forge World are the compressed ruins of thousands upon thousands of years of industry and ultra-technology. Much of which is haunted by archeotech data defence systems, or taken over by rogue or possessed Abominable Intelligences. All of these systems use people to stay alive. Some use people for hosts. Others inspire secret Cults who they then employ as maintenance workers and spies.
... Really, go find a copy of Paranoia somewhere and drop a pile of gothic on it.