The most interesting project is FreeRCT. It's homepage appears to be down at the moment and the project has no binary release yet. But a lot of work seems to have been done, and as FreeRCT attempts to create everything from code to graphics from scratch I can image it will take some time before it's complete. I'd love to see it completed though. A fully Free - both code and assets - game of this type would be really fun to have!
|Rollercoasters and roads in FreeRCT.|
|A slice of scenery from OpenRCT2.|