Does anyone know a way to change the text of the GUI elements in the standalone player, e.g the buttons 'Play' and 'Quit'?
I'm looking for a way to change this for language customization.
Not sure about windows, but on the Mac side, all the OS GUI is in .nib files located in the Resources folder in the application Bundle. You can edit these files in Apple's Interface builder, and change pretty much anything about the dialog box layout and labeling as you like.
Inside Game you can change your fonts to your language fonts in GUISkin. About standalone start dialog box you can use some softwares like resHacker to Change strings in dialog box.