Free coins

The currency in the game that can be used to buy resources and equipment without farming for it are coins. These are bought for real money via the in game shop.

However there is also the option to earn free coins by watching video adverts. This option is available in the shop page at the bottom.

Each video watched earns you 5 coins for usually around 30 seconds of your time. Not a lot, but you can keep watching them. So with a few taps twice a minute while you watch some TV, you can be well on your way to better gear or that omni-purpose workbench.