With reference to Starcraft, heavy metal is the name for the Terran strategy that almost exclusively employs Factory-produced units such as the Vulture and Siege Tank to both contain and attack an opponent.
Build Order:
8-supply depot
11-barracks
12-refinery
14/15-Factory
16/17-supply depot
18/19- Factory
If possible, create a
wallin with the first depot and barracks- heavy metal is extremely susceptible to rush strategies, as you don't often have many fighting units until the factory is completed. As soon as it is online, queue a number of vultures- and with your second factory, which should be completed about the time you have your third vulture, add a machine shop; you'll need it to obtain the two upgrades that make the entire strategy tick-
siege mode and
spider mines.
With heavy metal, spider mines are your friends. They deal 125 damage to units unfortunate enough to cross them, have generous amounts of splash damage, attack cloaked units, and come three to a pack with a free vulture included in the bargain! Mines will be your best tool against the ground forces that can close to melee range, and are also potent weapons against units with high HP values such as Dragoons and Ultralisks.
The other half of the equation focuses on the powerful siege tank. An apt commander will often lay a minefield directly in front of where he plans on attacking, and then set up his tanks behind the line. As they open fire, any units commanded to attack will face the force of the minefield as well as the rain of arclite hell from above.
As a general rule, heavy metal is the hands-down best strategy for a Terran player to use against a Protoss enemy. Zealots, Dragoons, and Dark Templar alike are all eaten alive by spider mines, and the fact that there are almost always siege tanks backing them up doesn't hurt at all- usually, you can contain a Protoss enemy with mines until he techs to Observers and can spot the mines from a distance- but during that time, you've done some teching and likely expanding of your own, and can field more tanks than your opponent can deal with. Against Terran and Zerg players, this stratagem suffers a bit- both races have detection that they can use to eliminate the mine threat, and both have the power to rush through a wallin before you can get set up. If your opponent is quiet, he can also obtain a group of air units and rain pain from above. The only easy answer to air units are Goliaths, and they are less than completely optimal against Mutalisks and cloaked Wraiths.