Successfully complete the game once on any difficulty setting and wait for the credits to end, then save the "Next Game" file to unlock "The Mercenaries" mini-game. Start a new game, choose that saved game, then select "The Mercenaries" mode. This mode involves controlling Carlos, Mikhal, or Nikoli from the train to the starting room with a two minute timer. Killing the various opponents and rescuing civilians during the journey will add extra money and more time to the clock. A rank and money will be awarded after the game is completed. The money can be used to purchase better weapons and infinite ammunition.