Step 1 of 9:

What is Amazon Underground?
Amazon Underground is an Android app that is in essence a third-party app store that can complement Google Play on your device. It's the regular Amazon shopping app with extras, and having installed the app on your phone or tablet you'll be able to access a new Amazon Underground apps and games menu that lists for download a selection of genuinely free premium apps and games - there are no hidden costs and no in-app purchases.
Developers of free apps make their money through in-app purchases and in-app advertising so what's changed? The difference here is that Amazon is paying those developers to waive their fees so that you can benefit from genuinely free premium apps such as OfficeSuite Professional 8, Goat Simulator, Fruit Ninja, Frozen Free Fall, Star Wars Rebels: Recon Missions, Angry Birds Slingshot Stella and more.
You can download these apps and games from Google Play, but by downloading them through Amazon instead you'll get full access without additional charges.
As a third-party app store Amazon Underground is in competition with Google Play, so you can't download it through Google Play itself. Here we explain how to download the Amazon Underground app and start downloading premium apps and games for free.