1. You can use coins to purchase boosters.

If you run out of some boosters, click on any boosters that you want to buy.

Let's say you have run out of rainbow balls and you want it.

You should pay 300 coins to receive 2 rainbow balls.

You can only buy boosters if they are all used. Used boosters will appear with + mark on the bottom right side of the boosters.

2. Moreover, you can continue the level if you fail a certain level by adding 5 moves and purchasing moves with 100 coins.