как делать skybox

Note that package contains several ready-to-use skyboxes - this is the quickest way to get started!

Drag the new Skybox Material to the Skybox Material slot in the Inspector.

Choose Edit->Render Settings from the menu bar.

To Assign the skybox to the scene you're working on:

Assign the 6 textures to each texture slot in the material. You can do this by dragging each texture from the Project View onto the corresponding slots.

Select the shader drop-down in the top of the Inspector, choose RenderFX->Skybox.

Create a new Material by choosing Assets->Create->Material from the menu bar.

For each texture you need to change the wrap mode from Repeat to Clamp. If you don't do this colors on the edges will not match up:

Make 6 textures that correspond to each of the 6 sides of the skybox and put them into your project's Assets folder.

A Skybox is a 6-sided cube that is drawn behind all graphics in the game. Here are the steps to create one:

Unity - How do I Make a Skybox?