Create a platform game using the existing sprites and backdrops: 1. Make the cat walk only when touching the green. 2. Make the cat jump. 3. Don't let the cat walk when touching the brown. 4. Make the cat advance levels (change the backdrop) when it gets the flower. 5. Make the cat die when touching the dark green and make the game end. 6. Make the game end when the last level is reached (and hide the cat and flower).
This was used to create a simple platform game as a lesson for a summer camp for kids. For something more advanced, try griffpatch_tutor's tutorial: https://scratch.mit.edu/projects/67727504/.