It is possible to restore Game Explorer on Windows 10, albeit with issues.
To do this, get gameux.dll, gameuxlegacygdfs.dll, and gameux.dll.mui, and replace the ones in your installation's system32 folder.
Then, run regsvr32 gameux.dll in an Administrator command prompt then reboot the PC.
Now you can't open it with just yet, now you need to use a Windows 10 1709 reference machine/VM, and export the following registry keys:
HKEY_CLASSES_ROOT\CLSID\{ED228FDF-9EA8-4870-83b1-96b02CFE0D52}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Desktop\NameSpace\{ED228FDF-9EA8-4870-83b1-96b02CFE0D52}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FolderDescriptions\{CAC52C1A-B53D-4edc-92D7-6B2E8AC19434}
HKEY_CLASSES_ROOT\CLSID\{06EEE695-542D-46F6-AEAB-FA2F1B2102D3}
HKEY_CLASSES_ROOT\CLSID\{6C5CFCDA-1F1A-4c9e-8D65-94771169D0B9}
HKEY_CLASSES_ROOT\CLSID\{709E2729-F883-441e-A877-ED3CEFC975E6}
HKEY_CLASSES_ROOT\CLSID\{9A5EA990-3034-4D6F-9128-01F3C61022BC}
HKEY_CLASSES_ROOT\CLSID\{CA22F5B1-E06F-4A2B-94FC-21E87FE53781}
HKEY_CLASSES_ROOT\CLSID\{DBC85A2C-C0DC-4961-B6E2-D28B62C11AD4}
HKEY_CLASSES_ROOT\CLSID\{E7B2FB72-D728-49B3-A5F2-18EBF5F1349E}
HKEY_CLASSES_ROOT\CLSID\{F382DA49-9148-4a22-AF78-C378DFC32D02}
Then, you need to merge it in your Windows 10 1803 (or above) OS. Note, that when importing, it is normal for you to get errors for some of the files, it is safe to ignore.
After that, you can open Game Explorer with shell:::{ed228fdf-9ea8-4870-83b1-96b02cfe0d52} (shell:games may work, but if it doesn't use the command mentioned before)
On newer versions than 1803, you will notice the icon for Game Explorer is missing, although the Game Explorer itself will open.
Note, that i recently discovered, that you cannot add new games by dragging them into the window. Maybe there's more things that need to be changed in the registry to get that to work
Update: I found out, that adding new games writes some registry keys in HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX. These are:
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX\S-1-5-21-2676120158-1310972984-2536851699-1000\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\ConfigInstallType: "4"
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX\S-1-5-21-2676120158-1310972984-2536851699-1000\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\ApplicationId: "{581C6B3F-904E-44CB-841D-81BB8F4052D3}"
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX\S-1-5-21-2676120158-1310972984-2536851699-1000\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\AppExePath: "C:\Users\Jevil\AppData\Local\Microsoft\Windows\GameExplorer\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\PlayTasks\0\Play.lnk"
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX\S-1-5-21-2676120158-1310972984-2536851699-1000\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\Title: "OneShot"
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\GameUX\S-1-5-21-2676120158-1310972984-2536851699-1000\{4BBF0B61-68E1-4CD2-BA5D-2147AD3BAAC4}\ConfigApplicationPath: "C:\Users\Jevil\Documents\OneShot"
The "Play" shortcut it links to is a link to the game executeable file.
However, after adding the registry key and folder to Windows 10, it still didn't get added. I don't know what to do to get the game to be added
