Guide for WorldBox

You can download the free official WorldBox - Sandbox God Simulator Android version (APK) directly from the Google Play Store. You can play the game for free, and to unlock some powers you can either watch some ads, or pay a one-time purchase. There's of course always this as well WorldBox (Free Mod APK Premium Free).

No, you cannot get WorldBox on PC for free.  Beware of websites promising you the game for free, as they can be filled with viruses or deceiving software.  You can buy the game on Steam directly. The developers don't approve of any other 3rd party websites, except Humble Bundle for early buyers.  Better not risk your PC by u sing shady websites. Also be wary of illegal file hosting websites, as using them can be illegal in many jurisdictions. Better safe than sorry.

WorldBox is free to play on iOS and Android devices! You can play most of the game for free, and unlock powers by watching advertisements. You can also unlock all powers for a one time purchase, which we call premium. On PC/Mac/Linux the game is available for a price. You can buy it directly on Steam.

No, you buy premium once and will receive all future updates for free.

Unfortunately there's no way to sync purchases between different platforms. Google Play Store, Apple Store and Steam are different services by different companies. Only store that allows to "sync" is humble store, which allows to add steam keys.