If you use a loading screen, you just get the loading screen image and nothing else. That's not very user-friendly. Can I add a line of text at the bottom to say "Press Enter to start game" (or something similar)?
Alternatively, is it acceptable to delete the loading_screen line and show the image manually in the on_startup{} section? Something like:
: print_graphic "loading_screen";
: print "Press any key to start";
: press_any_key;
(I'm writing this during lunch at work, so I'm not able to try it myself at the moment.)