There is also the https://www.openra.net/ project which provides reimplementations of the classic C&C games. Me and some friends played it a few times on Linux, OSX and Windows and it worked smoothly :)
Open RA takes some liberties and so isn't really a good comparision. https://github.com/TheAssemblyArmada and https://github.com/OpenDUNE/OpenDUNE are extremely faithful, and probably why this is happening (CCHyper from TheAssemblyArmada is on the community Council, for example).