Yes, This Stuff Is Fictitious - But Also So True

Games likely have a higher cultural significance than movies nowadays. They are not only more immersive (you are the center of the action after all, not just observing actions of others) and entertain you on a much longer time-scale, they also can create a much denser and sophisticated world than films can do.A good - and pretty spooky to be honest - example is Wolfenstein: The New Order. Just take a look at the gallery of the in-game propaganda poster the austrian newspaper der Standard has published:

(c) Bethesda softworks

(c) Bethesda softworks

(c) Bethesda softworks

(c) Bethesda softworks

(c) Bethesda softworks

Now don't tell me that's not scary! This glance on a world that has never been, but if history had taken a different turn, would been at least possible (ok, perhaps not cyborg-shepherd's dogs).

Wolfenstein is a perfect (even if pretty drastic) way to show you how subtle propaganda sneaks into people's conscience. Its artwork might look strangely scary, but also quite funny to us: nazi dog food - haha! But it is made in the very same hyperbolic style the real propaganda was. Hard on the limit of satirizing itself. This makes the Wolfenstein artwork so strong: It looks as if its just an inch away from a possible alternative history, catching up on the typical agitation and propaganda artwork of the first half of the 20th century.

My point is: yesterday it was propaganda. A pretty blunt in-your-face way of mass manipulation. In a world where you can't escape being bombarded with such imagery, you sooner or later just adapt it into your own mental world and know how to behave accordingly. such weird stuff actually worked!

Today the ways of manipulation are more subtle. But commercial advertisement campaigns or political spin-doctoring have just the very same goal: Infiltrate the public conscience with what they want you to think and how to believe.
The lie can't be too big really. You can still make people swallow it, if you just repeat it often enough and on large scale, people will build up tolerance. Its the same psychological mechanism.