How do i make a 2D planet with terrain (like in SimpleRockets)?

I want to make a 2D planet, but i don’t know where to start.
I want the terrain to look a bit like in SimpleRockets, also i don’t know if to make it from a sprite or a mesh.
Image : Imgur Link

Ugh! That game looks like complete garbage! All jokes aside, when I made the terrain for SimpleRockets I was using OpenGL so I used a mesh and I would recommend using a mesh in Unity as well. This looks like a great tutorial to get you started, though there might also be some assets that can help. As for collision, I’d recommend using PolygonCollider2d’s for each segment of the mesh using a copy of the mesh data (after dropping the Z-coordinates). Good luck!