It appears to be broken in the current build (whoops!), but you can (normally) specify a font filename on any label as part of the array, and DragonRuby will load the font it the first time it sees it used. If not specified, it uses "font.ttf". But again, this is broken in the current build. I'll get that fixed up.
(And also, font.ttf can be replaced outright. If dragonruby-package sees you have your own font.ttf copied into the game directory, it will leave it alone.)
> wait actually it is possible that this is a terrible idea for a game