There are many gaming systems out there that are better and cheaper than the rMBP.
A few months ago, I picked up an Asus gaming laptop for about $1200 and it had the same specs as high end MacBook Pro. Spent another $400 on 2x SSDs and 16GB of RAM, now this gaming laptop is a monster compared to the MacBook Pro. Sure it's 3-inches thick and weighs 10 lbs, but it's still portable and it never gets hot (nor do the fans spin up like crazy).