From Back of Box:
5 players... and much more!
Steam Park: Play Dirty introduces several new game mechanics. Change the core rules of the games with the "Park Directors." Use the "Espionage Dice" to spy on your competition and obtain more actions. Attract the "stingy Visitors" to gain some easy money. Plan new strategies thanks to the "Ride Extensions" and the new stands. And now you can even play with 5 players!