iac, let me assure you of two things. First, Jesus came not only to give you life, but to give you a more abundant life than you've ever known. Second, playing video games or watchig a movie does not condemn you in God's eyes.
If you feel it is wrong to play violent video games, then don't play them. When I first devoted myself whole-heartedly to Christ, I felt it was wrong for me to listen to secular music. For 3 years, I listened to nothing but Christian music, not because God told me to, but because I thought that's what God wanted me to do. Then I heard a song that I really liked by a secular artist. I prayed about it, and God spoke to my spirit that it was okay to listen to secular music that wasn't demeaning to Him or glorifying satan. Basically, I had listened to so much Christian music that it wasn't having a positive effect on me anymore, but a neutral effect, and God really spoke into my spirit that I had let my own notions of holiness create a stigma by which he never expected me to live.
I would suggest that you lay aside these things until you have peace in your spirit from God that it's okay to enjoy them. I do know that violent games and movies have a psychological tendancy to make us devalue human life, whether we realize it or not, and that is my greatest concern about these so-called "shooter" games. However, any arguments that school shootings or workplace violence is caused by such games is hogwash--evil people are going to do evil things and blame it on whatever is convenient. As for games affecting our behavior, I have been playing NASCAR Racing in some form or another almost daily for 9 years and have YET to ram a slow car off the road, spin an aggressive driver out, or cut through the grass to pass another vehicle--yet I've been doing those things almost every day for 9 years on the computer.
Bottom line, as zimmer said, your brain is like a computer--you put garbage in, you'll get garbage out. But, unlike the computer, you have the capacity to decide what's garbage and compare it to your knowledge of Biblical truth and decide which one to act upon. In this case, that's what you have to do--decide. And pray.
I hope somewhere in that rambling you can find a nugget of truth.