Another thing you could try is the following
- Open Terminal.app
- Write the following command:
xattrfollowed by a space and drag the SL.app from the Finder onto the terminal window - Press Enter, it should show
com.apple.quarantineas a result. If the text is not shown you’ve likely encountered another issue. - If the text is shown, type
xattr -cfollowed by a space and drag SL.app onto the terminal window again - Press Enter and try to launch the game again.