The Crystal Frog is a single player text adventure.
"I am in a small clearing in a field. There is nothing in the immediate area but grass all around. I can hear the birds singing in the summer sunshine, together with the fresh country air."
Thus starts the game, plunging the player straight into a text adventure where the object is to explore this land, find the eponymous Crystal Frog, and return with it. The player's progress is measured as a percentage score and the maximum possible score of 100% can only be achieved by visiting every location and using specific objects.