Mechwarrior 4: Mercenaries is a vehicle simulation video game for the PC released in 2002. It is a standalone expansion of Mechwarrior 4, based on the Battletech Mechwarrior game universe. It was announced on July 9, 2009 that Mechwarrior 4 Mercenaries and the Clan and Inner Sphere expansions will be re-released for free. As of April 22, 2010 the free release of MechWarrior 4 has been cleared by Microsoft.