Puzzle games focus on logical and conceptual challenges, although occasionally the games add time-pressure or other action-elements. Although many action games and adventure games involve puzzles such as obtaining inaccessible objects, a true puzzle game focuses on puzzle solving as the primary gameplay activity. Games usually involve shapes, colors, or symbols, and the player must directly or indirectly manipulate them into a specific pattern.
Rather than presenting a random collection of puzzles to solve, puzzle games typically offer a series of related puzzles that are a variation on a single theme. This theme could involve pattern recognition, logic, or understanding a process. These games usually have a simple set of rules, where players manipulate game pieces on a grid, network or other interaction space. Players must unravel clues in order to achieve some of victory condition, which will then allow them to advance to the next level. Completing each puzzle will usually lead to a more difficult challenge, although some games avoid exhausting the player by offering easier levels between more difficult ones.