Made some great progress with this today. Just managed to play crash bandicoot with an xbox 360 controller on moonlight on libreelec x64. I'm gonna try and iron the last few kinks then post a guide.
Got sound working now, Also got it booting first time. Need to fix the lag issue next.
To get this running Ive done the following:
1, Ive used the older libreelec addon moonlight 8.2.105 as this has controller addon support.
2, Installed Nvidia Geforce Experience 220.127.116.11 NVIDIA GeForce Experience 18.104.22.168 - Download - Filepuma.com
3, Blocked updates from installing as any other version on Geforce Experience stops Moonlight from working. Show hidden files and folders> Navigate to C:/ProgrameData/NVIDIACorporation> Delete any contents with in the folder > Right-click the Downloader folder > Properties > Security > Advanced > Add > Select a principal > Object name: Everyone > OK > Type = Deny, Basic permssions = tick "Write", untick everything else > Keep clicking OK until all properties are closed > Job well done!
4, Configure the settings in the addon but make sure the hardware acceleration is unselected, and audio settings do nothing.
5, Fix the sound with the guide from the following link Moonlight x86_64 sound fix. How-To
6, Reboot Libreelec and open the addon, you should be greeted with a code asking you to pair with your windows pc. DONT try to load a game yet.
7, Copy the contents of /storage/.cache/moonlight to /storage/.kodi/userdata/addon_data/script.moonlight/keys with file manager on libreelec or ftp server.
8, Reboot, Enjoy game-streaming
To reduce input lag, try 720p at 30fps and use a bitrate of 5000. Tested for a few hours with a xbox 360 controller and it booted everytime without a problem.