Effects of modern culture (Movies/Gaming) on karmic reactions

Well there are

• kamma that is dark & bright with dark & bright result
• kamma that is dark with dark result
• kamma that is bright with bright result
• kamma that is neither dark nor bright with neither dark nor bright result https://www.accesstoinsight.org/tipitaka/an/an04/an04.235.than.html

karmas that are useless in order to stop being a puthujjana = bright karma, dark karma, bright and dark karma.

SInce karma is a bad thing, the goal is to stop karma, you do not stop karma by creating more karma. You stop karma by spending your energy doing ''nonbright and non-dark karma'' which is the most neutral karma of all.

Now as usual, to evaluate the effect of an activity, or better a tendancy, you look at the results. Playing video games has nothing to do with the ''kamma that is neither dark nor bright with neither dark nor bright result'', so look at the other 3 karmas, which are useless to stop being a puthujjana:

"And what is kamma that is dark with dark result? There is the case where a certain person fabricates an injurious bodily fabrication, fabricates an injurious verbal fabrication, fabricates an injurious mental fabrication. Having fabricated an injurious bodily fabrication, having fabricated an injurious verbal fabrication, having fabricated an injurious mental fabrication, he rearises in an injurious world. On rearising in an injurious world, he is there touched by injurious contacts. Touched by injurious contacts, he experiences feelings that are exclusively painful, like those of the beings in hell. This is called kamma that is dark with dark result.

"And what is kamma that is bright with bright result? There is the case where a certain person fabricates a non-injurious bodily fabrication... a non-injurious verbal fabrication... a non-injurious mental fabrication... He rearises in a non-injurious world... There he is touched by non-injurious contacts... He experiences feelings that are exclusively pleasant, like those of the Ever-radiant Devas. This is called kamma that is bright with bright result.

"And what is kamma that is dark & bright with dark & bright result? There is the case where a certain person fabricates a bodily fabrication that is injurious & non-injurious... a verbal fabrication that is injurious & non-injurious... a mental fabrication that is injurious & non-injurious... He rearises in an injurious & non-injurious world... There he is touched by injurious & non-injurious contacts... He experiences injurious & non-injurious feelings, pleasure mingled with pain, like those of human beings, some devas, and some beings in the lower realms. This is called kamma that is dark & bright with dark & bright result.

During, after and before Playing video games, are you led to ''non-injurious bodily fabrication'' or to ''a verbal fabrication that is injurious & non-injurious'' or to ''fabricating an injurious verbal fabrication'' ?

Please see What does “ending karma” mean? and particularly this answer, it might give you some further insight into your question.

Shortly, karma is intention, if intention is noble, then it contributes to ending karma. We have Eightfold path, a path of Selfless deeds and ethics that end karma, since ending disease of Self and "mine" ends karma.

In 1611, Musashi began practicing zazen at the Myōshin-ji temple, where he met Nagaoka Sado, vassal to Hosokawa Tadaoki;

For many years thereafter he fought duels, killing many. Musashi studied Zen and Buddhism--they helped shape his inner life. He had deep insight and broad skills, not only in the martial arts, but also in the fine arts. He also violated the precept against killing.

To fight a duel effectively or play a video game effectively, one needs to be free of greed, hate and delusion. In the former case, one lives or dies in real equanimity. In the latter case, one does acquire some equanimity in the face of the game illusion, but it is weak and lacking any lasting satisfaction.

Game equanimity is weak because it arises in the context of "I am playing a game, and it will never hurt me". This weak equanimity rends like tissue paper in the winds of real change and real threats. And so we run into people who dream of living in the game, their selves safe for all imagined eternity.

Furthermore, numbed to reality by the games, we become intrigued by games that are connected to reality. Some play drone games, and real people die. But the self is still safe, so very safe. It feels immortal.

We can indeed learn something playing video games. We learn that illusion always disappoints. Knowing this, we can meditate and be done.

If we know the in-game "killing" isn't real, will this create any negative karmic effects?

I guess there may be two problems with it:

• It may be unlikely to create positive karmic effects -- I think that positive karma is associated with wealth and ease and so on -- see for example Sigalovada Sutta (DN 31) for an example of some of the Buddha's advice for lay-people (I remember it as the sutta of the "six directions").

• It may be (which I think is what RuthLydia's answer was saying) an activity that not associated with progress towards the ending of karma.

  I guess that playing video games is associated with sensual craving -- craving ongoing sensual stimulation.

  Instead perhaps you're supposed to find peace in the "unconditioned" ("unconditioned" meaning "doesn't have a cause") -- or possibly something to do with, beginning with, conditioned by, virtues (perhaps "good deeds" or "skilful" actions).

Also it might be worth mentioning the "Brahma-viharas" which are said to be, "the answer to all situations arising from social contact". Assuming that video games are a type of social contact, perhaps they're unskilful to whatever extent that they don't involve the Brahma-viharas (i.e. developing "good will" towards people, and so on).

As for movies, there's a sutta addressed to an actor (SN 42.2) which warns against acting, for which it reasons:

Any beings who are not devoid of passion to begin with, who are bound by the bond of passion, focus with even more passion on things inspiring passion presented by an actor on stage in the midst of a festival. Any beings who are not devoid of aversion to begin with, who are bound by the bond of aversion, focus with even more aversion on things inspiring aversion presented by an actor on stage in the midst of a festival. Any beings who are not devoid of delusion to begin with, who are bound by the bond of delusion, focus with even more delusion on things inspiring delusion presented by an actor on stage in the midst of a festival.

In other words, what's presented on the stage in a festival will tend to increase the Three poisons (i.e. desire, aversion, and ignorance).

From a hypothetical perspective, are these cultures being carefully prospered by the ruling class of this planet to keep individuals chained to Samsara for as long as possible?

I think you tend not to blame other people for your own lack of progress (e.g. "It's not my fault, it's his fault that I'm chained to samsara!").

When there is an opponent to enlightenment, an enemy, that's often portrayed as being Mara.