The Sumerian Game

From the introduction: "The Sumerian Game is one of the earliest known computer games and one of the most influential, alongside Spacewar! and Colossal Cave Adventure. However, its successor, Hamurabi, gained widespread popularity following the trajectory of the games by Steve Russell and Will Crowther, while The Sumerian Game remained confined to a small circle and eventually faded into obscurity. The rediscovery of The Sumerian Game is relatively recent, and its strong appeal to enthusiasts and researchers is partly due to its undeniable importance and partly to its status as a game seemingly lost forever."