Skybox: Blender 3D Game Engine

4.  Delete bottom half of cube.

Select only the bottom four verts:

Delete bottom four vertices.
3D View menu >> Mesh >> Delete >> Vertices
X Key >> Vertices

5.  Select the 4 side edges.  Mark as seams.

We want our UV map to have the same shape as the SkyBox texture that we are going to be using.

Cube selected.  Edit Mode

Edge select mode.
3D View menu >> Edge Select mode
Ctrl Tab 2

Select four side edges only

Mark seams
3D View menu >> Mesh >> Edges >> Mark Seam
Ctrl E key >> Mark Seam

6.  Add a material to the game object.  Set to Shadeless.

We don't want the inside of the skybox to reflect the light from the lamps.

Buttons Window menu >> Shading (F5) >> Material buttons
Links and Pipeline tab:
Link to Object
Add New

Set material to Shadeless
Buttons Window menu >> Panels >> Shading (F5) 
Material tab
Shadeless button

Download free seamless game textures or you can create your own seamless game textures. Use reference photos to add realism to the seamless texture you create. Textures let you create the style and mood for your computer game. Textures are a way to add detail and color to 3D graphics. Photo realistic textures add realism. Download free game models for your video game or create your own game models. Use the game models in First Person Shooter, role playing games, racing simulations and more. Download free textures to add detail to your game models. You can use the free game models you downloaded or model your own game models.