When I was testing something with #SimCity 2000's traffic routing I was thinking: "I wish there was a OpenTTD or OpenRCT2 of SimCity 2000"
There is actually a project that has started the work!
Current releases have focused on patching SimCity 2000 SE to run on modern (Windows) systems, and adding a modding API, but the first parts of the game have been reverse engineered and reimplemented in C++. Very cool!