Text air traffic controller - with fonts

I was thinking of the Apple II+ games of yore. There was an aircraft simulator in which the planes were different ascii characters and you brought them in.

I have this very halfbaked idea of a text game in which font sizes are used to give a third dimension to the visuals as characters would seem to recede away from the screen or come back at you.

Maybe this could be educational? Throw a letter at an advancing word which is missing some, completing it before it slams into the screen? Or change a word into another less dangerous word, Letterman style?