With large numbers of games installed the list of games becomes unwieldy and it is useful to modify applications.menu so that the Games menu has exactly one more level of menus (e.g. Card, Board, Arcade, Strategy, etc). These categories already exist to some extent in the debian packages, but some packages, like xmoto-edit are just 'Games' or use non-standard category names (like 'Arcade' instead of 'ArcadeGame'). Unfortunately for things like xmoto-edit there is to GameTool category or similar that I could see being used by any other packge, and in fact the editors for games seem to go in the same category as the game itself, so that is what I have done here.
So here is a .desktop file for xmoto-edit that adds the 'ArcadeGame' (and 'SportsGame' in case anyone wants to use that') category to the Categories= list so that the attached applications.menu will put in in the Games->Arcade menu
In fact xmoto-edit didn't have a .desktop at all (although xmoto does), so it wouldn't appear in the gnome menu, ever. Adding this .desktop to /usr/share/applications will fix that.
and the /etc/xdg/