I am also having the same issue. I have deleted and redownloaded the Game File like six times with no luck.
I uploaded "XNA Framework Redistributable" to the downloads. Run this msi file to install XNA Game Studio 4.0, then re-install Super Rad Raygun.
Good luck!
E: I guess the framework here is different than the one I got from microsoft, because it actually worked this time. (or maybe it's because I deleted my temp files it let me reinstall the framework instead of repairing)
