You are Gideon Braver Vandenburg, heir to the planet. While you were away, unknown attackers destroyed your home, killed your entire family, and stole the Chalice that you need to win the throne. When you are implicated in your own family's death, you are forced into exile. With a help of an old friend who contributed an old Jenner and some credits, you must become a mercenary. You must travel the Inner Sphere in search of clues to who set you up, and eventually avenge your family and recover the Chalice. You have five years. Good luck and good hunting.
Mechwarrior was the first 3D Battletech game developed. Dynamix (who later developed the Starsiege series) created it for Activision. You go to a planet and in search of fixers who will set up some contracts with the local authorities. The terms are a flat payment and some salvage payments. Some houses are very stingy but they tell you a lot about the mission. Others pay well but may not tell you everything. You can buy/sell/repair mechs, hire/fire pilots, decide which planet to move to, as you try to maintain decent relationships with all five houses of the Inner Sphere, while trying to uncover clues about where you need to go. This ground-breaking game is very replayable, as each mission is randomly generated. There's even some extended campaigns where you run 2-3 missions in a row.