I can speak about this topic first hand being a shooting victim and survivor with PTSD. In certain cases, especially in my case, PTSD can act as a catalyst for the expression of past traumas as well as the initial incident. It can be hard especially in the beginning when you are just realizing what your triggers are and how powerful flashbacks can be. You can survive a traumatic incident without developing PTSD (I think most likely your son's case) the person driving the car I was in didn't develop the disorder, nor the other two passengers. It is really hard to say what can help immediately after a truly devastating trauma, as I have a hard time remembering what all happened after mine. It's cool to hear about video games and I'll be interested in hearing what developments can be made further in this area.