CorsixTH aims to re-implement the game engine of Theme Hospital, and be able to load the original game data files. This means that you will need a purchased copy of Theme Hospital, or a copy of the demo, in order to use CorsixTH. After most of the original engine has been reimplemented in open source code, the project will serve as a base from which extensions and improvements to the original game can be made.

http://repo.openpandora.org/?page=detail&app=CorsixTH-CorsixTH-22523