Use the links at the top or bottom of the list to control sort order.
Put all the numbers in order -- left to right, top down.
Slider puzzles of 9, 16, and 25 tiles with grading and progress tracking.
Superclasses for your worlds and actors containing multiple useful methods.
An overview of what your subclasses of World and Actor may contain.
Clock simulation with a support class for decorating the background image of the world.