To unlock "The Mercenaries" mini-game, complete the game at any difficulty.

The object of the mini-game is to get from the Trolley to the starting point in Uptown within a limited amount of time. Additional time is awarded for killing monsters (and rescuing) people along the way.

Monster - Time (in seconds)
Crow - 1
Hunter - 6
Nemesis - 10
People - 20
Spider - 5
Zombie - 3