Ironic Fact: GFWL doesn’t really work with Windows 8 Pro x64.
Good Fact: it’s not that difficult to fix.
If GFWL isn’t working for you (best way to check is play a GFWL game and see if you can bring up the home menu. If not, it’s broken) here’s what to do.
NOTE: YOU MUST MUST MUST DO THESE STEPS EXACTLY. DON’T SKIP ON REBOOTING OR ANYTHING. ALSO MAKE SURE TO DOWNLOAD THE FILE I’VE LINKED TO, AND NOT ANY OTHER VERSION OF GFWL.
1\ uninstall both “Microsoft Games for Windows - LIVE Redistributable” AND “Microsoft Games for Windows Marketplace”
3\ download the GFWL installer from here.
4\ IMPORTANT: Right click the above installer, go to properties and change its compatibility to “Windows 7”. Save and exit.
5\ IMPORTANT: Right click the installer, and choose “Run as administrator”
6\ After it’s installed, run the GFWL game again. It should now work fine and redownload your profile.
Steps 4 and 5 are really, REALLY, REALLY important.