This quote is in the afterword to the first Wild Cards book by GRRM. I think it explains much about Game of Thrones.
"I never lost a game of Risk… After a while none of my friends dared to face me, so I set up the board in my bedroom and fight wars against myself, playing all six armies, inventing kings and generals, merrily invading, attacking, and betraying myself for hours."
George R R Martin. May 15, 2001