What Makes a Puzzle Hard? Search, Outcomes and Hidden Rules
Four things make a puzzle hard: a huge search, tests that reveal little, long solutions and hidden constraints. What the research shows for each.
Riddle10 blog
Articles about problem solving
What Makes a Good Puzzle? One Answer, Fair Clues and an Aha Step
A good puzzle has one answer, fair clues, a clear goal and an aha step. What research on logic, weighing and dissection puzzles shows about each.
How to Solve Brain Teasers: 8 Tools and When to Use Them
Eight solving tools matched to the four types of brain teaser, with five worked examples and the mistakes that trip people up.