The MechWarrior 4 'Mech paks expand gameplay for the bestselling and award-winning MechWarrior 4: Vengeance, based on the popular game of mechanized combat from FASA Studios. Each pak gives players new 'Mechs, a new electronics package, a new weapon, and a multiplayer map. Cyberlore, the team behind the successful MechWarrior 4: Black Knight expansion, developed the paks in conjunction with the FASA MechWarrior 4 team.

The Clan 'Mech pak contains the following four 'Mechs:

• Masakari: Easily identified by its squat torso, jutting head, and broad chest, this 'Mech has become notorious for its deadly accuracy (85 tons)
• Kodiak: A large, fast-moving Assault 'Mech that carries impressive medium-range firepower (100 tons)
• Arctic Wolf: Loaded with SRMs, this BattleMech can rapidly close with an enemy and shower it with more than 40 missiles (40 tons)
• Cauldron-Born: Named for the unstoppable zombies of Irish myth, this 'Mech can take immense damage and remain operational (65 tons)