In at least two hundred words, explain why “the garden of forking paths” can be seen as a “three-dimensional chess game.”

Borges's story The Garden of Forking Paths can be considered to be a three dimensional chess game for a variety of reasons.  First, like a game of chess, a nearly infinite number of possible outcomes are proposed through the story (just as how a chess game can allow for a variety of different outcomes).  Also, chess is a game of choice, just as the Garden of Forking Paths - both the story itself and the novel of the same titles mentioned in the story - allows for the reader to, in essence, choose their own design and strategy.  Furthermore, the lead character\protagonist in the story is manipulating events throughout the story to, in essence, score a "checkmate." 

Macbeth's "tomorrow and tomorrow and tomorrow" speech in Act 5, scene 5 acts as Macbeth's farewell. In it he thinks about the meaning of life and decides that death is something that comes to everyone, people are all just walking the earth with no importance. "Signifying nothing" at the end refers to man's life, it means nothing, according to Macbeth. He relates a person's life to an actor who plays a part on a stage for a couple hours and then disappears, doesn't exist anymore. 
This speech shows that he has essentially given up (in his mind) and thinks that life is meaningless.