I'm guessing by support you mean tutorials and examples (rather than meaning language/library support)? I actually found there to be a massive amount available (just look in the tutorial section) and there are also a lot of books to bring you up on the basics.
I also, find Unity 3D game engine and I find that I could programming there in C#, but again it doesn't have enough support for c#.
As I mentioned there are a lot of C# examples available right on the Unity site and in other places. You can definitely use the Unity to build an RTS as I prototyped one in pre-production in under two weeks when testing which technology we wanted to use going forward.