As the game develops it seems, at times, like any other conventional 2-D action role-playing game. In other words, as you progress and kill off your enemies with your equipped weapons, you'll gain experiences, which helps you gain levels. Pretty normal.
You'll see what makes this game different in that moment when you open up your inventory and find, like in Terraria or Minecraft, that you have the ability to create tons and tons of objects. For example, if you want to make a sword you'll need a sheet of bronze... and to make a sheet of bronze you'll need three pieces of bronze... and to find those, you'll have to break up rocks.
In addition to all that, you'll have a robot that will accompany your protagonist from the very beginning, and who you can use to take care of many different tasks. It could be anything from your bodyguard to your worker.
Epic Inventor is a really fun game, similar to Terraria in many aspects, but it's worth noting that this one is completely free.