HeroQuest is Milton Bradley's approach to a Dungeons & Dragons-style adventure game. One player acts as game master, revealing the maze-like dungeon piecemeal as the players wander. Up to four other players take on a character (wizard, elf, dwarf, or barbarian) and venture forth into dungeons on fantasy quests. Plastic miniatures and 3-D furniture make this game very approachable. Expansions were also released for this system.
The HeroQuest series consists of the main game and a number of expansions.
This game was made in cooperation with Games Workshop who designed the miniatures and helped in many of the production details including background world and art in the rule book and scenario book.
Additional material which is generally missed since it is not technically an expansion was published in the HeroQuest: Adventure Design Kit which did feature one more Heroquest adventure: A Plague of Zombies.
Other sources of HeroQuest supplements which are available (in some cases online.)