-Go to Settings->System->Display->Graphics settings

-Then click Browse and select Windows->Program Files (x86)->Steam->steamapps->common->Fallout 3 goty->Fallout3.exe

Once you selected Fallout3.exe it should appear under the "Browse" button, click it and then choose options under it. Select High performance and save

-Then click Browse again and choose Windows->Program Files (x86)->Steam->steamapps->common->Fallout 3 goty->FalloutLauncherSteam.exe

FalloutLauncherSteam.exe should now also appear under the "Browse" button. Click it and select High performance and save again (Be sure to do this to both Fallout3.exe and FalloutLauncherSteam.exe, otherwise it might not work). Now close your settings window and go to Steam and enjoy playing Fallout 3 :)

Hope this helped you out if you were wondering how to get it working :)

If this doesnt work try out this one
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=2667221447