The Basics:
Dungeon, published in 1975 by TSR, was deisgned by Gary Gygax, Michael Gray, and S. Schwab.
Why Dungeon is Part of the Games Timeline:
Dungeon helped introduce the world of Dungeons and Dragons to even more players.
Here are the other games I believe are the most culturally and historically significant games published since 1800.
More About Dungeon:
A simple boardgame version of Dungeons and Dragons, Dungeon challenged players to find a certain amount of treasure in the dungeon and then escape. Naturally enough, the treasure is protected by monsters. Combat is simulated via dice rolls.
