Go (game)
Go is an abstract strategy board game for two players, in which the aim is to surround more territory than the opponent. The game was invented in China more than 2,500 years ago and is believed to be the oldest board game continuously played to the present day. 
A 2016 survey by the International Go Federation's 75 member nations found that there are over 46 million people worldwide who know how to play Go and over 20 million current players, the majority of whom live in East Asia.
Netrek
Developed as a successor to 1986's "Xtrek", "Netrek" was first played in 1988. It was the third Internet game, the first Internet team game, and as of 2011 is the oldest Internet game still actively played. It pioneered many technologies used in later games and has been cited as prior art in patent disputes. "Xtrek" and "Netrek" are the oldest games of what is now called the MOBA genre.