The game has numerous changes to it than the two previous games. One of these changes is the absence of the isometric view. There is an option to change to the isometric view. The game uses full 3-D visability. For the first time, you can make "Peeps". Peeps are the guests and visitors (as known in RollerCoaster Tycoon 1 and RollerCoaster Tycoon 2) that come to your park. The game also allows you to ride the rides in the park for the first time.
RCT3 has 16 scenarios, with 5 already unlocked. You must complete Apprentice level first to unlock 13 of the 16 scenarios. Certain scenarios are unlocked by completing Entrepreneur or Tycoon level. You can also create your own scenario aswell.
A new addition to RCT3 is making your own park, known as a Sandbox. You have an unlimited amount of money and use all your rides. This is a good way to start as you have unlimited oppurtunities. You can change the terrain aswell. The possibilities are endless in Sandbox.
Peeps, also known as Guests in RCT, are the visitors of the park. They come to the park, ride your rides, throw up, spend all their money, use the bathrooms, drown, whatever they do at your park. You can also make your own custom peeps with the brand new Peep Creator that comes with RCT3.