For the past several years I have periodically offered a seminar on Puzzles, Games, and Problem Solving. The theme of the seminar is Puzzle-based learning. Zbigniew Michalewicz, Nick Falkner, and Ed Meyer have been working in this area for several years. Our collective pedagogical experience has been shared in our recent book Guide to Teaching Puzzle-based Learning Springer, 2014
The pedagogical objectives of project-based learning include dealing with ambiguity and complexity, integration of a variety of approaches, user-testing of the value of proposed solutions, and working with a team of people with diverse backgrounds and skills. In problem-based learning we use domain specific knowledge (for, for example, electromagnetism, data-structures, circuit-theory, accounting etc.) to solve problems in the domain. In both problem and project-based learning the problem drives the learning: students need to assess what they already know, what they need to know to address the problem, and how to bridge the knowledge/skill gap. Puzzle-based learning focuses on domain independent transferable skills of critical thinking and abstract reasoning. In addition, puzzle-based learning aims to foster introspection and reflection on the personal problem solving process. What was I thinking? What is the solution? Why did I not see it?