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.
Board wargame
The actual subject matter of wargames is broad, and many approaches have been taken over the years towards the goals of simulating wars on a grand or personal scale. Some of the more popular movements constitute established subgenres of their own that most wargamers will recognize.
The oldest of the subgenres, and the one that still retains "iconic" status for board wargaming as a whole, it got its start with the first board wargame, "Tactics" (which, ironically, used a square grid; hexes were a slightly later innovation), and is still used in many wargames today.