We deserve to know which idiot decided 'video games' would be the Republican response to mass...

Have you watched the ‘kids’ play any of those games? I did for about 5 seconds, years ago and told the grandson that I did not approve of that type of game! CW5 Jack Cardwell

Top, no one called half the country deplorable. First off, half the country did not then nor now support Trump. And, Clinton was referring to the white nationalist that were vocally supporting Trump. And yes, those are deplorables.

MSG Stan Hutchison - Oh no? I remember when Mitt Romney was vilified for saying something analogous.

To take the original post at face value, what we are talking about is what we who do Information Operations call Themes and Messages. You give a planned "message" in order to develop understanding along the lines of what you want the perceived truth to be. It can be true or not, the key is employing it in response to or in advance of a competing, "enemy" theme or message.
The left's theme on mass shootings is to take away the tools used, the guns. Gun control is a theme for them for more than one reason, and not all of them are noble. That is ok; I understand what they are doing. So anticipating this, the GOP would plan and circulate competing messages - such as pertaining to mental health, addressing the shooter, not the tool, because they want to preserve access to the tools for law-abiding citizens. In this case, the GOP clumsily employed what we call counter-messaging, going after the causal factors for mass shootings. It is certainly worth studying if cultural factors such as our consumption of violet movies, TV, video games, and other media has coarsened our mentality to the point that morality is skewed. However, in actual execution, the "violent video games" message fell flat, and was mocked rightly by sane-thinking Americans.
The messengers did not understand the point of that particular message, and flubbed it.

Personally, I think the real issue is the breakdown of families, social contact, and morality throughout America. There is a festering there where loners strive to belong to something, find other loners and social outcasts to hang out with, and the sickness and antisocial feeling grows until they resort to this kind of terrible act.
The truth is, the vast majority of the weapons used in mass shootings are not "assault rifles", and nearly all of them were purchased legally from a licensed dealer after a background check. I don't see how you close access to the weapons themselves without depriving law-abiding Americans a Constitution specified right.

1SG (Join to see) - Top, you make some valid points. Personally, I do not think we can point at one single factor as to the cause. In a free society such as ours, it will always be difficult to prevent such actions, regardless of actions taken.