With the ever increasing amount of violent games on the market it is important that we know how to pick games that are appropriate for our children. The VSC are the governing body who set the age limits on them. Their website not only explains age ratings but also tells you how to set up parental controls and age restrictions on all devices. It is definitely worth a look. We will be using these resources in upper KS2 this year. 
http://videostandards.org.uk/Schools/