First make the PONG game
Lesson 12 – http://learnscratch.org/sc3-u3/sc3-l12
Another video for Pong http://www.youtube.com/watch?v=EzROnRfLwbk
PONG for 2 Players http://scratch.mit.edu/projects/mistermitchell/38201
Now make the CAT and DOG game http://www.oneil.com.au/pc/scratch/Scratch-Lesson-3.pdf
Musical travel is cool http://www.learnscratch.org/sc3-u6/sc3-l28
Now chose something you want to make with either Scratch or Sploder