Lots of competitions vs other players… Would make the game more interesting/fun and add new way to gift boosters if add Statistics - measure performance, etc
Example of some metrics which could be tracked for each user / along with milestones that could give a reward
Total levels pass w/ 3 stars
% of total levels w/3 stars vs all levels
Total levels pass w/ 3 moves or less
Number of levels passed in 1 try / % of levels passed in 1 try vs all levels
Count of each colored candy over all levels / count of total boosters used
You get the point - maybe give free boosters for reaching a milestone