Silver coins are the other currency in the game, and can be used to buy boosters that give you a head start in levels. You can buy these boosters before the start of any level. To learn more about headstart boosters, please refer to the FAQ “What are Headstart Boosters?” under the “Gameplay” section!
Silver coins can be earned in various ways. Scattered through the map along the level path are crates full of silver coins, tapping one of these crates will add the coins to your total! Silver coins are also rewarded for the first time you beat a level. If you replay a previously completed level and beat it again, you will still earn some silver coins, but a much smaller amount.
Additionally, you can exchange gold coins for silver coins. Tapping on the silver coin balance in the top right of the screen will open the Silver Shop, where you can spend your gold coins on more silver coins.