PING REDUX

I’m not too sure on the exact number of stars needed but I unlocked this at 163 not really a guide but this is more of a baseline

Edit - Someone has just confirmed that this unlocks at 162 stars !

With each world having 10 levels and a boss with which to get 3 stars, you can average about 2 stars per level with a few 1 stars to unlock levels (later levels being quite a bit annoying to do 3 stars).

Stars required to unlock worlds:

• World 2: 18 stars

• World 3: 36 stars

• World 4: 54 stars

• World 5: 72 stars

• World 6: 90 stars

• World 7: 108 stars

• World 8: 126 stars

• World 9: 144 stars

• World 10: 162 stars

• World 11: 180 stars

• World 12: 198 stars

Here's a youtube video to help beat some of those levels: