MS continues to force certain features on their users and with the Fall Creators update, the controversial Game Mode is now enabled by default with no way to switch it on or off unless you edit the registry.
As Game Mode only really works with games from the Windows store, and is suspected to cause issues with other games, you may want to disable it on your sim PC.
Here's how its done:
https://www.addictivetips.com/windows-tips/disable-game-mode-in-fall-creators-update-windows-10/