Dungeon Explorer is an action/role-playing game released for the TurboGrafx-16/PC Engine in 1989. It centered around the quest of several heroes to find the Ora Stone for the former king of Oddesia. When the alien race that now rules the land invaded, the stone was hidden deep in the dungeons of the land by the King to keep it safe. Now, however, the king wants the players to recover the stone, which can bring life, light, and happiness, and to kill the alien king, Natas: King Satan. The heroes progress through several different dungeons and fight fearsome bosses such as Bullbeast and Grimrose, and finally recover the Ora stone. Upon giving it to the king, however, the king reveals himself as Natas and steals the stone. Additionally, a guard named Judas also betrays the heroes, but is defeated by them. The adventurers then chase and confront Natas, killing him and taking back the Ora stone and ushering in a time of peace.
Players can play as a fighter, thief, warlock, witch, bishop, elf, bard, or knome. Special classes, like the Princess and Harmet, can also be unlocked as the game progresses. The classes vary primarily in their black and white potion abilities. For example, the Bishop's white potion heals nearby allies, whereas the Bard's black potion has the ability to change the music. The game supports up to five players simultaneously. All extra lives are shared between players. The game also features a password system that tracks the player's level, class, and four base stats (attack, strength, agility, and intelligence).
Source: Wikipedia, "Dungeon Explorer", available under the CC-BY-SA License.