its physically impossible, the game has Voxels like physics, the game is basically a pixel 2d sandbox, every pixel is square sized 0.5 , if you would want to make a perfect circle you cant, the squares dont have a ending, its just a sharp 1 by 1 1:1 block
A fun game you can play is to place a bunch of humans down and set a random events to overdrive and see how long you can keep them alive. As you can see in the picture i trapped the remaining humans in a water tank which worked well until they froze out of nowhere. you could also try to keep a building or structure intact but its fun trying to keep these puny humans from dying horribly.