After crash landing on an unexplored planet you are left with nothing but a few tools and your imagination. Make yourself a shelter, secure food and water and start building towards making a spaceship capable of interplanetary travels.
Planet Nomads is a true sandbox game with procedurally generated planets, total creative freedom to build all kinds of things big or small (100+ building blocks already), and planets ranging from desolate wastelands to delicate forest environments and rocky plains.
You can try the building part demo of the game already. Download the Editor for free from the game's official website.