I remember this on the Intellivision, in the mid 80s. The cards and the number pad were directional shooting. The different colors of mountains indicated the difficulty. If you were skilled enough, you could make it to the cloudy mountain to retrieve the crown and become the new king of the land. Different monsters, various items needed to advance helped each playthrough feel unique.
It's practically impossible to find or play anywhere any more, and deserves to be preserved and/or rereleased.