The Mind of a Master Brain Teaser

Mr. Kim belongs to an elite cadre of "puzzle masters" who spend their days building logical mazes and brain teasers. In more than 20 years as a professional puzzle designer, Mr. Kim has worked on everything from word, number and logic puzzles to toys such as Railroad Rush Hour and computer games such as "Obsidian" and "Escher Interactive," which features interactive puzzles based on M.C. Escher's optical illusions. Lately, he has been developing smartphone game apps and contributing a bimonthly puzzle column to Psychology Today. [Read on]