What is Mine Craft?

'A game where your children can go anywhere with anyone they want to, in dark caves, in rain and anywhere - there are no rules.' To quote the advertisment.
 
Imagine - would you let them do this in real life?
 
Of Course not.
 
So what is the difference?
 
Would it not happen to your family?
 
These things happen to others?
 
Which games are your children using to talk to strangers around the world?
 
Yes they are.
 
No, are you sure?
 
How are you sure?