While you may at first think of an actual puzzle when you read the description for a puzzle PC game that falls under this category, puzzle games are actually much more varied and can be much more intense than a jigsaw although you can literally complete a puzzle online as well. Typically however, puzzle PC games have more to do with logic or mazes.
Most of the games that are listed in the puzzle game genre are mixed with adventure games that have mini puzzles or games that require logic or are educational games that are designed to stimulate and motivate the brain. The most popular puzzle game that almost everyone recognizes is Tetris, although in reality Tetris is more an action game than a logic game.
However, due to the fact that the puzzle game genre is very open many games are tossed into the puzzle category when the creators or distributors are not sure where they should be placed. In fact, music games were often considered puzzle games before a separate genre was completed which is why often you will find that some titles in the puzzle genre that are not very closely related.
Mazes are a very large part of puzzle games as well as hidden object games which is why I spy, Luxor, and Bejeweled are some of the top puzzle games available online although they do not fit into the technical description of a puzzle logic game and have more to do with precision time or close observation.
