

It’s an interesting thought, one that has crossed my mind a time or two.
I think in reality, we don’t have anything that is “absolute” mind control, but we come pretty close through long-term exposure to biased information (propaganda). You asked for this to be an exception, so I won’t go into details there.
There is a famous study done by Olds and Milner in the world of psychology, where they hooked up rats’ reward center in the brain to some electrodes, resulting in incredible change of behavior. The rats were stimulated by them pulling a lever, and this felt so rewarding to them that they couldn’t think of anything else. After the stimuli was given, they kept pulling the lever to exhaustion, not even prioritizing food or sleep anymore. The scientists also attempted the reverse; to inhibit the reward system. The rats became lethargic, and didn’t have motivation to do anything at all, not even eat.
This is, to much smaller degree, effectively the same that happens with humans that are addicted. Whether it’s to gambling, porn, drugs, gaming, or social media.
So if one can spontaneously create an addiction in someone, you’re one step closer to mind control.
One show that caused a bit of a psychological unease with me was first season of Jessica Jones, where David Tennant makes an excellent performance of a character who can make anyone do exactly as he says. I think this is the kind of mind control that we fear, where we are completely aware of ourselves, but cannot help but do what we have been commanded to do.
Edit:
I forgot to answer your question: Yes, I think it will be invented (and to some degree already has), and total mind control is probably at least 50 years away, as we research the psychological basis that was found with the aforementioned research.
It’s fun that one can use games for it, but it shouldn’t be difficult to do the same through AI-generated imagery either, which isn’t much more difficult.
Even though this method is flawed, one shouldn’t really use ID-only verification either imho, as it’s a security risk to upload any official document like that (ref. Tea app leaks).
The whole age verification that the UK wants to impose has been quite the impossible task from the beginning. Creating government-backed education for (future) parents about how to raise a kid and protect them in today’s digital society would be more efficient than this, if we really are thinking of what is best for the kids. But alas, there are zero requirements to become a parent…