SexyScheme is a C#-based implementation of R5RS.
I created this project mostly for fun--to have a C# project to hack on that wasn't work-related.
Since this project is mostly for fun, I haven't made strict R5RS compliance my top priority. As a result there may be glaring issues in the implementation (for example, no proper tail recursion--yet!), but I don't let those issues hold back progress.