Tried following thisguide. Downloaded the 1.3 version from 12/4 based on Thorin’s recommendation in comments. Installed on Win 10 (64), crashes every time I try to start the application no matter what I try; Compatibility settings, starting from terminal, changing menu driver in cfg file, 32 bit version, older versions.
Nothing works, instant crashes every time.
Ideas?
Would you be willing to run it through gdb to get a backtrace? If so, you can download it from here: http://www.equation.com/servlet/equation.cmd?fa=gdb
Put gdb in the same directory as retroarch.exe, open a command window there and type:
gdb.exe retroarch.exe
Then, at the gdb prompt, type:
run
It will probably crash as it usually does at that point but it should hopefully tell us why 
I see the OP hasn’t continued to pursue this issue. I was having the same issue so I would like help on this. I downloaded GDB but I can’t make out how you were trying to direct on what exactly to do.
OK. So I just kept looking at old post and finally found one and it said I had to install directx 9 to get RetroArch to work with Windows 10. I did that and got RetroArch to open now. But, is there not some kind of work around this or at least an update coming that will allow RetroArch to run on Windows 10 using directX 12? Its seems pretty stupid to have to go back to directX 9.
You are not going back to directx9, actually most likely you are using the opengl renderer. DirectX12 doesn’t deprecate DX9, it builds on top of it, you are likely to need dx9 for lots of PC games too.