Diagram of memory game play added

Before I start coding anything, I want to try to understand how the game play works, the logic and events involved. Making this diagram to visualize it is helpful to me.
Update diagram to include the idea of a turn, and define the point at which a game starts

Turns may be useful in the future for keeping score: the score should probably reflect not just the time taken to complete the game, but also how many times tiles were flipped. In other words, does completing the game in fewer turns indicate greater skill? The start of the game is also moved so that it is registered after the first tile is flipped, not when the board first appears.