Primitive Units. QuadVees. Superheavy 'Mechs. Weapons of Mass Destruction. Robotic and Drone Systems. Land-Air BattleMechs. As you delve into BattleTech lore, additional weapons, units and rules become available to you and your forces as you fight in the Dark Age, Jihad, or even the depths of the Star League Eras, and all the way back into the Age of War before the birth of the BattleMech. Alternate Eras introduces a huge swath of rules for playing across the thousand years of BattleTech history, including weapons and equipment mostly unique to a given era. Note: The original publication of Interstellar Operations had rules for large scale BattleTech play (Strategic BattleForce, Abstract Combat System, and Inner Sphere at War) which can now be found in the Interstellar Operations: BattleForce.