This study is focused on the challenges in puzzle video games. Based on several previous studies, the researcher created seven different types of challenges in puzzle games. To study the key of challenging levels in puzzle games, three games were chosen, then walkthrough videos of these games were watched and challenges were noted and categorized into different types. The collected data showed that different puzzle games have different challenge types while abstract reasoning is the most common challenge in every puzzle game. The total challenge numbers and pacing in puzzle video games strongly depend on the design intention of the game. And The number of challenge types has no direct connection with difficulty. The category of seven types of challenges and the results of this study may bring reference and inspiration to future studies. It may also shed some light on puzzle game design.