This might be a stupid question, but I hope someone might answer my question.
Yes it’s possible. But it’s nonstandard and they won’t publish your game with the custom font.
But can I write a game, host it somewhere, never publish it, and have it use that font?
Yes. You can.
You have to mess around with http://choicescriptdev.wikia.com/wiki/Style.css
Mess around? How? I’m interested!
If you follow the link it will explain.
style.css is one of the files in the choicescript folder you usually don’t touch.