You’re thinking in far too limited a scope. It can be as basic as implanting certain ideas about how tasks are performed through the structure of gameplay.
Hell, it could just be implanting newly developed subliminal messaging through background acoustics, or adjusting the general mood of themes.
Oh, that’s even more engineered and conspiratorial than I was thinking. You’re right.
I mean, it’s just musing on what is possible. Certainly the motive exists to explore whatever is possible.
Hell, if you want conspiracy: They could train a generation from a specific culture on heroic epics, then train another generation of the global population with grievance porn to create villains.