OpenRCT2
An open source re-implementation of RollerCoaster Tycoon 2
...The player must try to make a profit and maintain a good park reputation whilst keeping the guests happy. OpenRCT2 allows for both scenario and sandbox play. Scenarios require the player to complete a certain objective in a set time limit whilst sandbox allows the player to build a more flexible park with optionally no restrictions or finance. RollerCoaster Tycoon 2 was originally written by Chris Sawyer in x86 assembly.