Most people think of Clue for a classic deduction game. For me my favorite older deduction game is Sleuth. It has some similarities to Clue, but it is deduction in its purest form. One piece of jewelry is left in the box and it is the job of the players to find out which one is missing. There are three aspects to each card - color, gem type, and number of gems. You need to be able to answer what all three of those aspects in order to win.
Generally the only questions you can ask are using the cards dealt in front of you - and as you use them they are replaced. So part of the struggle is getting the information you need using the questions you have been provided. However, you will also get lots of information on other peoples turns if you are paying attention to the information they receive. You might even get just as much information as they get - making it so you are always engaged as the role of active player goes around the table.
When it is your turn there are two types of questions you have the ability to ask. If you ask about only one aspect the player you are interrogating just says the number of those they have out loud for all to hear. Sometimes though you ask about two aspects at the same time. In that case everyone will find out how many they have that match but you get to see the cards themselves. Knowing exactly which ones to eliminate can sometimes be the margin of victory.
Sleuth is a great simple game but it does take time to learn how best to take notes and definitely shouldn’t be played at the higher player counts the box suggests. But when played with four players who want to work out a logic puzzle competitively there is nothing quite like a great game of Sleuth.