Mathematician, co-founder of combinatorial game theory.
There is a short biography mentioning Go here written by J J O'Connor and E F Robertson.
An extract on the topic of Surreal Numbers is
Conway was not trying to develop number systems, but rather was analysing the game of Go. Conway studied the games of two players of Go at Cambridge who were of international standard. He noticed that near the end of a game it appeared like the sum of a lot of smaller games. Analysing the situation Conway discovered that certain games behaved like numbers and surreal numbers were born
Kaiou: He invented the solitaire pastime (game) of " Life", on a goban. Nothing to do with Go but it is interesting to try. "Life" is played on an infinite board, with every cell alive or dead, every step deciding the next status of each cell simultaneously.
The 2015 biography of Conway, Genius at Play, the Curious Mind of John Horton Conway by Siobhan Roberts, has many mentions of the game Go, including a diagram of a game between Jon Diamond and Paul Prescott from the 1974 British Championship which illustrates Conway's observation that the endgame appears to be a sum of smaller games.