I am creating a game that I have created a terrain for. I really like the terrain so I am wanting to keep it but I want to have the game take place on a full planet. Avoiding paying $200 for an asset already made, how would I develop something to allow me to "tile" this terrain to make a full planet and to make it round instead of flat? I know this has to be somewhat possible with the expensive assets on the asset store that are for round terrains. I just need to figure out how and I can't find anything online that is much help.
I don't think Unity provides any default component or tool to create spherical terrains. You can create a world and a mesh procedurally, needs some coding. You can either change the transform of gameobjects to another point when you collide with them, which you can write inside OnTriggerEnter().
In your case, you could do a little hardwork and make the spherical terrain using a 3D application like Blender. Best of luck :)