Just to be sure, but by "appropriate settings" you mean these, right?
- Open Terminal.app
- Write the following command:
xattrfollowed by a space and drag the TFTUV.app or 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 -d com.apple.quarantinefollowed by a space and drag TFTUV.app or SL.app onto the terminal window again - Press Enter and try to launch the game again.
If the above doesn't fix things you could also go into the application bundle by right-clicking SL.app > Show package contents and navigating to /Contents/MacOS, drop the "SL" file into a terminal window and press enter. This should start the game from the commandline. If the game doesn't start from there, there should be error output in the terminal window, could you copy/paste that here, the output in log.txt would be helpful as well?