Game gore

I went into game the store to checkout some pre owned for my 6 year old boy. I also had in tow my 3 and 4.5 year old. Walking round the store in the metrocentre I was a bit disturbed by the amount of gore on view. There was a tv at kids head height playing a cut scene from a game where a character walked around executing other characters by blowing their brains out as they begged for mercy. Also there are many cover designs depicting gore, death and violence. I don't mind it personally as I am old enough to filter the rubbish I see. Unfortunately my children are not old enough to understand. I do not want my kids exposed to it so I recommend the shop display PG, 15 or even 18 certifications if they are playing and displaying violence.
Also a note about the staff playing on the kinect in the main area of the shop. I do not appreciate them shoving my kids out of the way because the staff, who are supposed to be working are more concerned about their game. Next time I may not be so restricted and I may take my complaint face to face in the car park if my kids are treated in such a manner.