I'm not entirely sure how exactly you could make the game much more metal. I guess you can't crush your battle opponent's balls.
When the trees can kill you and beasts made of blood and chains roam the world, when everything is an evil are and where the only savior is METAL. Also a bunch of references to heavy metal bands would be nice.
Trees can absolutely kill you in DF. Have you not been killed by trees yet? Also
http://dwarffortresswiki.org/index.php/DF2014:Blood_man and
http://dwarffortresswiki.org/index.php/DF2014:Iron_man is already a thing. And putnam,
yes you can.
But going metal means turning everything up to 11 all the time, right?
For starts, you can do more that is literally metal. You could make trees out of metal. Either try to change the properties of wood to be like metal, or use actual metal tags in trees. You can use the tags from Iron Man and Bronze Colossus to make metal versions of their normal animals. I had been trying to do a mod where animals have metal bones that you can melt down after butchering them, but I had trouble figuring it out. You could make metals appear more frequently or appear as layers instead of clusters and veins. You could check out The Earth Strikes Back mod for some ideas that making mining more dangerous.
You could make guitars. Sometime soon the new version which will have actual musicians will be released and guitars would be actually useful. Or, you could make combat guitar weapons.
Have you ever read Edgar Rice Burroughs novels? He invented some very metal universes before metal was a thing. ERB has made a lot of specific things that you can definitely mod into DF. I think it would be easier to take a real world-building adventure and mod it in, rather than try to translate the concept of Metal into a game that is already very metal.
^Edgar Riceburrough's vision of Mars, "Barsoom".
One of my favorites are the Mahars of Pellucidar. They are giant pterodactyls (specifically a descendant of rhamphoryncus, props for paleobiology, ERB) who cannot hear but can communicate telepathically. They are highly intelligent and possess scientific advancement far beyond that of the humans of Pellucidar. The Mahar keep Thipdars, larger, less intelligent pterosaurs described as dragon-like and are allies of sagoths, gorilla-like men who love to fight. Mahar keep humans as pets and slaves, and some even consume them as livestock.
You can find information about ERB worlds on the internet.
http://www.angelfire.com/tv2/phobeg/pel.htmhttp://www.erblist.com/abg/plantsanimals.htmlI made a list of creatures for an ERBesque Sword and Sorcery mod that I'm probably not going to get around to modding
http://www.bay12forums.com/smf/index.php?topic=153439.msg6545750#msg6545750 Feel free to borrow.