Classical 15 Puzzle was invented in 19th century and is a sliding puzzle that consists of a frame of numbered from 1 to 15 square tiles in random order with one tile missing. The object of the puzzle is to place the tiles in order by making sliding moves that use the empty space. 15 Puzzle 21st Century has the same object but the tiles are not necessarily numbered from 1 to 15. They can be labeled by almost everything - numbers (not necessarily sequential) from any range and type (positive, negative, fractional, hexadecimal, etc.), letters, distances, weights, temperatures and so on. The current version (1.0.0) of the game includes 10 different play modes. Features: Random shuffling. Hint mode - shows which tiles have been already placed to their right spots. Timer. Moves counter. Hints counter. Pause - manual (triggered by the player) and automatic (triggered by external events like incoming calls,etc.). History of the games - records player name, play mode, date/time, play time, number of moves, number of hints. Subjects of the Game (Play Modes): Numbers: Positive Whole Numbers (1-15) - Classical Fifteen Puzzle. Positive Whole Numbers (1-999) - Any whole numbers from 1 to 999. Positive and Negative Whole Numbers - Any whole numbers from -99 to 99. Positive Fractional and Whole Numbers - Any numbers from 0 to 9. Hexadecimal and Decimal Numbers - Hexadecimal and Decimal numbers from 0 to 255. Letters: English Letters (A-Z) - Single English letters from A to Z. Combinations of English Letters - 3 letter Combinations like "ark", "jep", etc. Conversion of Units: Distances (miles,kilometers) - Distances from 1 mile to 99 kilometers. Temperatures (Fahrenheit,Celsius) - Temperatures from -9C to 99F. Weights (pounds,kilograms) - Weights from 1 kg to 98 lb.