Scratch

Learn how to cause a sprite to walk toward the mouse pointer and freeze in place if it catches the mouse pointer.  Also learn how to create a 3D effect with the sprite becoming smaller and smaller as it walks toward the horizon.

http://scratch.mit.edu/projects/dbal/173385

Find a complete explanation of the code at:

http://www.dickbaldwin.com/homeschool/Hs00124.htm