3M, 1967, 3-7 players, ages 10 and up. Another in the series of 3M "Bookshelf" games created by prolific game designer Sid Sackson, Sleuth is an exercise in abstract detection and deduction (think "Clue", just more sterile). At the beginning of the game, one card is removed from the deck of 36 "gem" cards. The remaining cards are then dealt out to the players, who must then deduce which card is missing by asking questions of the other players. Each gem card has three properties associated with it - a color (red, yellow, blue or green), a symbol (opal, diamond or pearl), and a number (single, pair, or cluster-of-three). EG - three blue opals, one red diamond, etc. Each player has a score sheet with a box for each of the 36 cards. After eliminating the obvious (the ones they were dealt), players are then dealt four "question" cards which they use to find out which gem cards the other players do (or don't) have.
Question cards are either very specific ("Show me your yellow opals") or more generic ("How many pairs do you have"). In the case of the specific questions, the askee must actually show the cards in question to the asker (who then marks them off on their score sheet). Other players do not get to see the actual cards. However, since they know the question and the number of cards in question, they can (hopefully) use the information to deduce what the cards were (or at least work towards narrowing things down). For the more generic questions, the asker does not get to see the cards in question. Some question cards are "wildcards", allowing the asker to fill in the blanks in order to come up with a more "customized" question.
After each question has been asked, the player draws a new question card and play continues to the next player. If a player decides he doesn't like any of his questions, he can skip a turn and draw four fresh cards. Once a player thinks he has figured out the missing card he can "solve the case" by looking at the set-aside card. If correct, he is the winner. If incorrect, he must spend the rest of the game simply answering questions (he cannot guess a second time).
The real trick is to be able to use the questions and answers on other players' turns to help narrow down the field of "suspect" cards. Unfortunately, you really lose that advantage if people spend more turns asking you questions than they do the other players (since answering questions about your own cards gains you virtually nothing in the way of useful information). And woe unto you if you ever screw up your deductions and mark off an incorrect card on your sheet (as you're pretty much screwed at that point).
Overall, Sleuth is a mildly entertaining game that's easy to learn and plays quickly. I guess it's good for a break between other games, but probably not compelling enough on its own to build an entire day of gaming around. I think it works best with 3-4 players (any more than that and the difficulty factor starts to go through the roof).