The 3-letter mystery word game. 1. Take turns being the "spy" and choosing a spy word from any card. 2. Detectives play their cards one at a time. The "spy" tells them the number of letters their words have in common with the "spy word". 3. Using their super sleuth powers of deduction, detectives narrow down the letters in common with the "spy word" with every card played. 4. The first player to guess the 3-letter mystery word wins the round!