Glad you are enjoying the game!
Right now you cannot switch to ASCII due to how we are distributing the game (web is GFX only, and the downloadable versions are either GFX or ASCII, but separate.
Future versions will allow switching the UI either from a launcher (initially) or game settings (a bit more complex, might come later on), which will allow jumping back and forth as needed (game data is abstract and share-able between UIs).