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.
Lexiko
In 1931, Butts wrote a paper entitled "Study of Games." In his paper, he described three categories of games: board, number games using playing cards or dice, and letter games (or games that fell into more than one). He noted that, although the most popular games were of the first two (e.g. Chess and Backgammon), the best letter game readily available was Anagrams. Around that time, he was reading "The Gold Bug" by Edgar Allan Poe and noticed a line containing the English letter distribution. This gave him an epiphany: Anagrams would be more fun if the most common letters in English were more common in the game. He carefully analyzed letter frequencies in newspapers and other printed works to determine the ideal letter distribution for the game. With a few other changes, he named his project "Lexiko". The game design was rejected by games manufacturers such as Parker Brothers and Milton Bradley, but Butts was able to sell copies on his own, though not enough to recoup his development expenses. In 1938, he began work on a board game based on "Lexiko", which he called "Criss-Cross Words", which was eventually renamed "Scrabble".