I've also heard that love itself is a game, but that version of the saying isn't as accurate, in my opinion. Love is more complicated and it's harder to state in a metaphor. I like the quote that says the course of true love never did run smooth. It's from one of Shakespeare's plays, but I don't know which one. Anyway, love isn't really a game. And it probably is smooth sailing sometimes. Or maybe not. Life itself isn't easy, so why should love be unproblematic? Ah well.
Other things that are like games are conversations, tests, including the GRE, according to the prep class I'm taking, and probably a lot of other things. And I know that using "like" makes it a simile, but that's still a kind of metaphor. I still like the game of telephone analogy the best, though. To me it describes both the frustration that arises from miscommunications and the joy and laughter that we can generally find if we look for them and refuse to take ourselves too seriously. It makes life a lot more fun.