Their certinaly could be a correlation, judging from forums I've posted on. I'm not sure why it is, I think metal is quite an escapist(ahh, the pun, it hurts) form of music and I think games are often quite escapist things, so they appeal to the same audience looking for that type of thing I suppose.
Suprisingly enough, out of the gamers I know in real life, a very small majority my age seem to be metalheads. I know a fair few metal heads and the most they play is GTA and CoD MW 2. I have a friend a few years older than me though and his older crowd of friends who are now in their early 20s or there abouts, from what I've seen of them, are all massive metal heads and gamers.
So yea, no conclusions can be drawn as of yet.