Similar to the movie The Game (1997): real-life game, mysteries to solve

[Melissa (Distracted by New Grandbaby)]

In the movie the main character is given the birthday gift of an elaborate reality game where the people he comes into contact with and the situations he is in are all parts of this game. I'd love a similar book, preferably not sci-fi or fantasy but one that is realistic fiction. And not The Da Vinci Code please, although that one is similarly themed, I disliked it.
I liked Ready Player One (yes, I know, breaks my sci fi rule) and Mr. Penumbra's 24 Hour Bookstore, those are kind of what I'm looking for, but not exactly.
I adored The Westing Game as a kid, it remains one of my all time favorite books.

[Scott]

Glasshouse
The Crimson Labyrinth

Sorry the first one is SF.

[Rachel]

You might enjoy Night Film - it's not about a game as such, but a mystery where the main character feels he is being set up. Gets very surreal in places.

[Gillian]

Another book where a character feels like they're being set up to do something is I Am the Messenger by Markus Zusak.

You also might like Midnight at the Bright Ideas Bookstore by Matthew J. Sullivan.

Finally, you sound like you might like books based around augmented reality games, although those are likely to be sci-fi.