For sight-impaired players, there should be an option
to have the game speak various aspects of the
interface. For example, as a new comet appears, say
its equation aloud. When the player types numbers, say
each number aloud. (In the latter, we may want to make
this optional, since some players will be more
comfortable with keyboards, and won't need typing
feedback. Also, the typed-digit sounds should sound
different than other gameplay voices.)