Free puzzles online are a collection of games that exercise the player's critical thinking skills. The games can be categorized into classical turn-based board games, such as chess and mahjong, as well as newer imaginative physics based games and word games. The board games are variations of beginner level chess or checkers or math related games like sudoku. Mahjong and matching games are memory related puzzle games that test the players visual perception skills. Physics based games are the most interesting because these games feature unique puzzles based on gravity or other physical aspects as envisioned by the game developers. Most physics games are level based and get progressively harder on each level.