This time in the form of an opinion piece by Alvin Monje on Gamasutra
On closer inspection, however, even this level of recognition is grossly inadequate. In creating Dungeons & Dragons, Gygax and co-creator Dave Arneson didn't just build a blueprint for the digital RPGs to come; they built the progenitor of most contemporary video games, irrespective of genre.
In providing these rules and model of the world, D&D offered a powerful framework for running the first interactive simulations of reality, one in which both the everyday and the extraordinary were possible. For the first time in gaming, you could walk around a world, talk to people, explore towns and cities -- and, yes, dungeons.
The simulations ran on the best computers around: human brains. Armed with common sense knowledge, intuition, and imagination, a person need only hear the word "forest" or "castle" in order to picture one. (This worked out well, since building a convincing digital forest in 1974 was impossible.)