'Dream Park/The Voodoo Game' by Larry Niven en Steven Barnes (London Pan Books 1991, 0-330-32055-6)
What an excellent book! For anyone who is fond of role playing games,
this is a must!
The basic story-line however is the solving of a murder. You don't have to worry about this often-used theme, because it is masterfully entwined with the rest of the story. In fact, this murder has its feedback on how the game proceeds.
You just have to read it, it's really worth it!