Well, in the context of the discussion, you can "teach" Emacs to play Pacman. Imagine sending left/right/up/down commands to a Pac-Man emulator or whatever. The emulator itself may not "understand" these commands in pure text, accepting some digital form of them, but whatever format it accepts, it probably can be reduced to sequences of alphanumerical characters.

Similarly, when the emulator broadcasts current coordinates for pieces, or sprites of them - they still can be reduced to plain text.

As a matter of fact, if you want to play Pacman in Emacs... you can just play Pacman in Emacs: https://github.com/emacsmirror/pacmacs