question for Englanders

I am going to be stuck in London's heathrow airport for something like
six hours in a couple of weeks.  Since you can't get anything GZG in
Austria
(where I normally live) without ordering it, I though I might use my
time
profitably by wandering around London and buying stuff.  Are there any
game
shops that you can get to from Heathrow in a couple of hours by public
transportation?  Or is this just wishful thinking?

Thanks for any advice,

SJR