Nothingness: you could use simple thick carton squares. On one side you have a questionmark, on the other side the espionage piece. I admit it wouldn't look attractive, but it's simple and effective. The only difference with the real game is that you know when your opponent detected a piece.
(hide) In the mood for a quick game that is guaranteed to finish within 2 hours? Create a new game of your preference, select the Time for game and set Time to 0 days / 1 hour, Bonus to 0 days / 0 hours and Limit to 0 days / 1 hours. (TeamBundy) (show all tips)