Crazy seeing reviews about levels being 'too hard' well if it were easy what's the point? That being said, I'm at the 4th 'world' & while I have made purchases.. I've also beat hard levels after trying multiple times by figuring out a stradegy after my failed attempts! It feels awesome beating a level I've been stuck on (without making a purchase) and that's what I appreciate about the game :) I think the creators give plenty of free sources to attain boosters! Love playing to subside my anxiety