A BattleMech represents the pinnacle of military technology in the third millenium. Developed using advanced technology, the BattleMech is a hulking titan of destruction. BattleMechs, usually abbreviated 'Mechs (Though this term could also refer to IndustrialMechs, the BattleMech's non-combat relative), mount dozens of types of high-powered weaponry and armour so heavy that they are commonly be measured in tons.
The BattleMech could not exist without many technologies humanity has yet to develop: The two most important being the 'Mech's artificial musculature ("Myomer") and the Fusion Engine with which to power it. When a current is run through the Myomer, it contracts, much like a human muscle. The Fusion Engine provides extreme amounts of power from simple water, however it does generate a significant amount of heat. Another advanced technology in use is the "Heat Sink," which is an advanced device that pumps heat out of the 'Mech. Without Heat Sinks, the heat generated by a 'Mech's Fusion Engine and its weapon systems would quickly reach critical levels and impair normal function or even kill the pilot.
All the same, the primary component of a BattleMech is its Fusion Engine. While an IndustrialMech runs off of normal Fossil-Fuel Engines, the power produced by such devices is not great enough to power their larger cousins. The Fusion Engine is also the most expensive part of a BattleMech, and its destruction is usually what puts a BattleMech out of the fight. However, it is worth mentioning that destruction of a 'Mech's cockpit will kill the pilot, also downing the 'Mech. If the 'Mech's Engine is damaged badly enough to crack the vacuum-seal around its plasma core, oxygen will rush in and be superheated. The thermal expansion of this oxygen will manifest in an explosion-like detonation in a wide radius around the 'Mech. It is wise to be far away when this happens.However, normally, the Fusion Engine is not damaged in this way. It is also the Fusion Engine that separates the BattleMech from its smaller ilk, the contemporary battle tanks. While some tanks are rigged with nuclear engines, the BattleMech's extreme mobility keeps it on top of its rudimentary cousins. This Engine is also what allows a BattleMech to utilize Energy Weapon technology. Due to the engine's prohibitive cost, however, contemporary armoured units continue to be seen on the battlefields of the inner sphere.
'Mechs are classified by Chassis and Weight Class. Chassis defines what 'Mech exactly is being dealt with, Weight Class is a much more general descriptor of the typical work the 'Mech will be used for.
Industrial Mechs are occasionally seen on the battlefield. Their design rarely exceeds 20 Tons. Buzz saws, flamethrowers, and other industrial devices are seen on these 'Mechs. Their fossil-fuel engines provide very little speed, despite their small chassis.
Light Mechs are the Scouts of the battlefield, generally built up to 35 Tons. They act as harriers and spotters for the larger 'Mechs. They rely on their speed more than their armour to keep them protected. Weaving in-between the legs of the larger 'Mechs, they can stymie an advance while keeping enemy tension high. If they are ignored, they will be able to quickly break through the weak rear armour on most 'Mechs in no time.
Medium Mech are the "Workhorses" of the battlefield. Weighting from 35 to 50 Tons, they are multitaskers, able to act as front-line combatants, scouts, and fire-support emplacements. Medium 'Mechs are the most common type of 'Mech. They will not last long under the barrage of fire from an Assault-Class 'Mech, but their speed is often top-notch to compliment their heavier array of weapons.
Heavy Mechs are the Big Brothers. Carrying many smaller weapons or a few very heavy ones, these are the heavy-hitters, able to swat down their lighter cousins with relative ease. The speed on some makes is still very surprising (The Dragon's base chassis runs at 94.4Km/H), and their armour will absorb many hits before being finally destroyed.
Assault Mechs are the kings of terror on the battlefield. Weighing up to 100 Tons, these beasts are slow, heavily-armoured, and carry a bristling array of weapons with which to pulverize any enemies in sight. One-on-one, only another Assault 'Mech will be able to down an Assault 'Mech without large amounts of luck or skill. However, their lack of speed makes them vulnerable to being torn apart by a mob of smaller 'Mechs. If Assault 'Mechs are not supported by the other members of their Lances, they will quickly fall.
Weapons are generalized under three broad types: Energy, Ballistic, and Missile, each with respective effects on a 'Mech and its target.
Ballistic weapons are the most conventional military devices, ranging from simple machine-guns and autocannons to the powerful Gauss Rifle. These weapons are difficult to aim and require a significant tonnage allocated to ammunition, but are powerful and steady weapons to build a 'Mech on.
Missile weapons are divided between two groups, Short-Range Missiles and Long-Range Missiles. SRM are dumb-fire, high-damage missile racks that fire up to 6 rockets. LRM are lock-on, low-damage missile racks that fire up to 20 guided missiles. Streak Missiles are also available, enhancing the SRM with a lock-on capability. Missiles are medium-heat, medium-accuracy, low-damage, and (depending on the number of missiles) fairly light on ammunition requirements.
Energy weapons are the most futuristic weaponry, relying on the energy output from the 'Mech's Fusion Engine. These range from high-powered Lasers to the exotic Particle Projectile Cannon. They are in general highly-accurate, medium-damage lasers. They generate high amounts of heat, but do not require ammunition. However, the tonnage allocated to another weapon system's ammunition will ordinarily be spent on additional heat sinks to keep the weapons firing. A bonus of using laser weaponry is that an enemy 'Mech will absorb a small amount of heat.