It’s a move that comes around maybe once or twice in a lifetime. It’s perfect, it’s obvious but only in hindsight, it changes the course of the game. In the game Go, it’s the divine move.
Go has a great set of terms to describe board positions, types of moves, and more abstract descriptions of the game state. The divine move, also known as the Move of God, is my favourite of them all.
Wikipedia describes two specific divine moves. The first was in an 1846 game called the “ear-reddening game.” An 8-dan master faced a much younger 4-dan player; the younger player made a divine move and one of the audience members saw the older master’s ears redden in surprise. (The younger player won the match by two points, and went on to become one of the most famous Go players of the 19th century.)
The second divine move mentioned came about in 2016, when Lee Sedol was playing the AlphaGo AI: Lee Sedol won the match as a result of that inspired move. (It was the only match in the 5-game series that he won.)
The Generalist Academy 
For the Ear-Reddening Game, Honinbo Shusaku (the younger player) actually won the match by two points.
You’re absolutely correct, thank you! I don’t know how that error got in – I’ve corrected the post.