The term the devs use to describe it is a construction sandbox. Basically you're dropped on an alien planet with a small robotic vehicle called a tech, and you can mine natural resources like trees and rocks to refine and sell off world. You can also use the raw materials to create new parts for your vehicle. There are rival techs out doing the same thing you are, so you need to protect yourself and your base as well. The late game gets pretty interesting, you can build hovering vehicles and planes.

The vehicles are built from blocks and other parts, so there's a little bit of Minecraft influence. The original TerraTech has a basic story mode in place, but it's primarily designed to be a sandbox. The new one has been in early access for just over a week, so not a lot of content to this point.