How can I make the game to show player's actual score in the GUI status bar?
@SCORE@. As easy as it gets. In the manual under "Editing the GUIs".
You can also write @SCORETEXT@ to show what their current score is out of e.g. 10/20 I think.
Oh...
10Q I didn't know!
OK, since this is clearly covered in the manual...
LOCKED.