BattleTech is the most richly detailed game setting ever created the BattleTech universe started as a board game and has been expanded through over 100 novels, three major video game franchises (MechWarrior, MechCommander, and MechAssault), a cartoon, an RPG, dozens upon dozens of game sourcebooks and supplements and literally hundreds of miniatures. All the while only requiring a single boxed set that can last through hundreds of hours of play time all by itself.
BattleTech the game: BattleTech is a tactical wargame that is played on hexmaps or with tabletop terrain, and with miniatures or counters. Combat units come in many varieties: BattleMechs (large walking tanks), aerospace fighters, VTOLS, tanks, battle armor, infantry, protomechs, and more. It is a strange hybrid of board game, miniature wargame, and RPG with rules supplements to emphasize whichever aspect appeals to a player most.
You can find out more about the BattleTech universe and game here: Leap into the action!
Chaos Campaign rules system: The Chaos Campaign e-book is a free download, providing the core rules for the open-ended "track" campaign framework. This source enables gamemasters and players to use a variety of published tracks (such as those found in the Jihad Plot Sourcebooks of Blake Ascending, Jihad Hot Spots: 3072, Jihad Hot Spots: 3076 and the Jihad Turning Points e-books) and combine it with forces of their own creation to play out pivotal moments in BattleTech history.
You can download the Chaos Campaign rules system for free here.
