Make the font install automaticaly. I experimented with this and there was one big problem. The game has to be started with administrator rights, otherwise it won't work. A small hurdle, but some people might not be able to do that. Plus there were other smaller problems with that system
Show a message that a font is missing. This is what I did. If the font is not installed, the game shows you a message and the installation instructions. Then it simply closes down untill the user installs said font. If that is not enough, then I don't know anything else will.
So that's basicaly it. I removed old versions and added this new one. If you have the font, nothing happens. If it's missing, the game will warn you and tell you what to do. Everything else is the same.