It would be a good idea to add a new Forum section to discuss CityMania development. As far as I can deduce from the github logs, this is a one man project, but like OpenTTD, I believe the CityMania client will age like fine wine, and more devs will discover this over time.
It could be useful to have a section to discuss new features, bug reports, and generally provide an on-ramp for new contributors.
I was able to build the client on Ubuntu, the process was quite simple! But navigating the codebase is another issue, I'm not new to C++, but I am new to the OpenTTD code, and could use some tips on where to go dig for knowledge and resources related to development. And also how CityMania is integrated into the base OpenTTD, how it's separated and what not.
I know writing documentation is every developers favorite past time, but doesn't hurt to ask :-P