World War 2 makes sense. Futuristic sci-fi seems reasonable, too. Halo was a stretch, but they made it work. But trying to make a real-time strategy game about heavy metal is clearly madness, the sort of thing that even Ozzy Osbourne's addled grey matter wouldn't come up with.
Full credit to Double Fine, then, for working out a solution that the Brummie lunatic would agree with.
In fact, every part of this open-world action game is built from heavy metal references, musical in-jokes and Jack Black. It's dedicated, it's inventive, and to begin with it's very funny - but it doesn't last.
Things start promisingly with a genuinely hilarious opening, in which hard-bitten roadie Eddie Riggs is sucked into a Black Sabbath-fired netherworld after an accident at the pop-rock gig he's grudgingly curating. The comedy is perfect and the attention to detail is spot-on.
Everything from the menu screen to the casual one-liners dropped by the other characters raises a smile. The character of Eddie, voiced by Jack Black, is a direct descendant of his role in School of Rock. The open-world lovingly recreates classic album covers and gives you the freedom to motor round finding them between missions - with the likes of Motörhead and DragonForce playing on the car radio, of course.
It even pulls off the near-impossible feat of making quicktime events fun: you strum through a sort of mini-Guitar Hero riff to summon spells.
It's charming. It's inventive. It is, undoubtedly, the most metal game ever made. But after a while the gags tail off, the in-jokes wear thin, and you realise you're plodding through missions that are at best indifferent and at worst infuriating.
The RTS challenges are the backbone: you're defending your stage and attacking the enemy's. Harvest fan geysers by building merchandise booths on them, and spend their adoration on units like headbangers (melee attack) and roadies (stealth). On paper it sounds great, but in action it's irrelevant because you don't have any fine control.
While it's possible to send different units to do different tasks, it's extremely fiddly and invariably ends in disaster because your other units are too dim to look after themselves unaided. You finish up just sending everybody charging forwards at once, and discovering that actually, on Normal difficulty that's all it takes - once you've slapped up some merch booths and unlocked the heavier units, just keep rushing the enemy until you win.
Other missions are little more than minigames. Escort tasks just involve driving behind the tour bus holding the fire button. Rounding up Metal Beasts is just driving in circles holding a button.
Dungeon crawling is wandering through a cave zapping spiders. True, you're zapping them by strumming your guitar to call down lightning bolts, but the novelty soon fades. It feels like it's come out alongside the latest Pixar movie, not something that has Lemmy from Motörhead as the healer.
Beyond the main story, the world is filled with side quests, but they're all variations on a handful of simple themes - the chief attraction is playing Spot The Album Cover Reference, and if you aren't intimately familiar with Judas Priest then it's just a bit dull.
This wouldn't matter if the story kept the laughs coming, but after the brilliant start things get steadily more functional and less entertaining.
It's not a bad game, just disappointing if you were expecting something as brilliant as Double Fine's last release, Psychonauts. Instead, this feels like a licensed game. A very inventive one, certainly, but one that shares the problem they all have: it feels like it started with the subject matter and cobbled an overly simplistic game around it, rather than nailing the game design first and adding the references afterwards.