If you don't use boosts you can not get pass levels that are higher in number. You need 30 people and the game will give you 29 just so u have to repeat and repeat or use boosts. I can not keep spending money's. It's a terrible game would like to see it changed in some ways. And the rewards are carp you get one thing each time it does not matter if ur on level 5 or level 100 , just one reward.