Here's the situation: My son and I share the same computer, I have the admin account and he has a regular user account. He plays Genshin Impact and every time he wants to play he needs me to input my admin password.
Is there a way to stop that? Can I just make that single executable file have special permissions and leave everything else as is?
every time he wants to play he needs me to input my admin password.
It depends on the App. If the App (say like Sync Back Pro) provides a Manifest file or like method to permit Standard Users to run the App, then you can.
If the App does not provide a feature like this (many Apps do not) then only a Administrator can start the App and you cannot do what you are suggesting.