Review of Dungeons & Dragons powered by the Slant community.
Maybe it was not the first role-playing game using dices, scenarios and complex rules with direct interaction with a dungeon master, but it was arguably one of the most popular, including in its variation Advanced Dungeon & Dragons, and it made the genre so popular.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Big Influence on the Genre
Pro Classic Representative of Pen & Paper Roleplaying
Although it probably wasn't the first of its kind, it is what springs to mind when thinking of the genre.