The Royal Game of Ur is the oldest board game for which we have a near-complete set of rules. People were playing it five thousand years ago, and it is still played today.
The game plays like backgammon but with four-sided dice. You can see an example of the gameplay in the video below. Two players race their pieces around a track, bumping each other back to the start and trying to be the first to get all their pieces to the end. Thanks Itti-Marduk-Balāṭu, for being the first rulebook editor in history!
Well, that was fun!!
Played as late as the 1950s among the Jewish population of Malabar, Wikipedia tells me.