eighties, starring Jack Black, who before he became a household name was already doing this type of homage with his Tenacious D act. And if you're in the target audience and you've never seen it, I recommend digging up a Tencacious D concert... and don't be put off if you were unimpressed by the Tencacious D movie from a couple of years ago.
Getting back to the game, I noticed that Jack Black's character, "Eddie", bore a resemeblance to the character of Eddie from the Rocky Horror Picture Show. Eddie in RHPS was played by Meatloaf, who happened to play Jack Black's father in that Tenacious D movie. Coincidence?