I've been more peaceful, both with myself and others, since extremely reducing violent and sexual media exposure.
Of course, this could work the other way as well, as I become more peaceful, my desire to virtually knock peoples' heads off with a shovel isn't as prolific. Probably the two work together. Our thought patterns mimic what we are exposed to. In a similar way a child will learn to solve problems through rage if his/her parents solve problems through rage. Our attitudes and internal functioning will mimic what we indulge in, regardless if our exterior actions do or not.
I had extreme road rage during the years I indulged in violent games and media.
I no longer do.
Correlation? Causation? I certainly don't have any tangible evidence for this apart from noticing those things in my life that change at the same time. I've also gone vegan in this time, grew closer to God, started to read more, and moved away from old friends. Any of these could be connected as well. A look at my posts from the last few months compared to a year or more ago should serve as evidence to the renewal (that I attribute to Christ, you may take it as you will).
But like I said, just sayin'.
Try a media fast some time for yourselves just to see. A month with no games or tv.
Perhaps games do impact us. Just as tv. Just as our friends. Just as most environmental factors.