Hero: Immortal King takes the concepts of a traditional role-playing game, and turns it into a head-to-head (or solitaire) card game between the adventurers and the dungeon. One player leads the adventurers down three dangerous corridors (each represented by a deck of cards), while the other player manages the dungeon and its dangers. The adventurers win by defeating the final monster in the dungeon. The dungeon wins if the adventurers lose all their Courage - represented by tokens.

The Den of Dementia is infested by all sorts of bubbleyes - nasty floating orbs with their eyes on the adventurers' demise!