MechWarrior 4: Vengeance is a vehicle simulation game, developed by FASA Interactive and published by Microsoft. It was released on November 22, 2000. It is the fourth game in MechWarrior series. It takes place in BattleTech universe where the pinnacle of all war machines are huge, heavily armed robots called BattleMechs. The player pilots one of these "'Mechs" and uses variety of available weapons (autocannons, lasers, missiles, and more) to battle enemy 'Mechs, tanks and other vehicles. An expansion pack, MechWarrior 4: Black Knight, was released in 2001, and a subsequent stand-alone expansion, MechWarrior 4: Mercenaries, was released on November 7, 2002. Two smaller expansions, Inner Sphere Mech Pak and Clan Mech Pak, were also released in 2002.