Can You Solve These 5 'Easy' Retrograde Puzzles?
Earlier this year, Chess.com included a brief mention of the death of renowned logician Raymond Smullyan, who often used chess as the medium for his puzzle creations. He was quite the chessic sorcerer -- even his picture above makes him look like a wizard!
The sample "retrograde" puzzle that was included solicited quite a response in the comments section. With that in mind, we will stoke your interest with five more puzzles that mostly require the reader to think backward instead of forward. They are ordered in terms of difficulty, from one to three pawns.
You can put your answers and explanations in the comments, but for a real challenge, try to solve them first before seeing what others have conjured!
1) From the starting chess position, how could this position below be reached after exactly four moves for each side? The moves don't have to be good, they just have to be legal. 
2) We promise that in the position below, there is only one square the White king could legally be on (but there is one!). Which square is it, and what were the last few moves to explain how he got there?
3) White had a few too many before playing this game below, and opened with 1. f3, 2. Kf2, 3. Kg3, 4. Kh4 (call it the "Accelerated Yifan"). What four Black moves were played to produce a checkmate on the White king on Black's fourth move? Note that Black's moves alternate with White's, just as in a real game, and also that Black cannot allow White to make an illegal move by walking into check. For example, Black cannot play 1. f3 e5 2. Kf2 Qg5 because then White's required 3. Kg3 would be illegal.
4) This may seem like a carbon-copy of puzzle #1, but we assure you it is much harder. From the normal starting position, how could both sides play exactly four moves to reach this position? Remember, it must be four for each side, not four for White and three for Black.
5) We can't forgot about the Retrograde Jedi himself. Our final puzzle comes from Raymond Smullyan's "The Chess Mysteries of Sherlock Holmes" (a great book to be stranded on a desert island with).
There can be only piece on h4, and Smullyan won't even tell you the color. Which piece is it, and which army did it come from?
Unless you've seen these before or you a fellow retrograde wizard, you may be wondering why we defined them as "easy." Well, believe it or not, some puzzles of this ilk are actually much, much harder!
If you are stumped, or if you have some or all of the solutions, read the comments below! We will post the official answers in the comments in a few weeks.
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Mike Klein began playing chess at the age of four in Charlotte, NC. In 1986, he lost to Josh Waitzkin at the National Championship featured in the movie "Searching for Bobby Fischer." A year later, Mike became the youngest member of the very first All-America Chess Team, and was on the team a total of eight times. In 1988, he won the K-3 National Championship, and eventually became North Carolina's youngest-ever master. In 1996, he won clear first for under-2250 players in the top section of the World Open. Mike has taught chess full-time for a dozen years in New York City and Charlotte, with his students and teams winning many national championships. He now works at Chess.com as a Senior Journalist and at ChessKid.com as the Chief Chess Officer. In 2012, 2015, and 2018, he was awarded Chess Journalist of the Year by the Chess Journalists of America. He has also previously won other awards from the CJA such as Best Tournament Report, and also several writing awards for mainstream newspapers. His chess writing and personal travels have now brought him to more than 85 countries.
