In August 2002, Microsoft released two add-ons to MechWarrior 4: Vengeance: Clan 'Mech Pak and Inner Sphere 'Mech Pak. Each pack contained four new BattleMechs and a few other bonuses, such as new weapons.

Clan Mech Pak includes:
- Arctic Wolf
- Cauldron-Born
- Kodiak
- Masakari