Before computer graphics, movies relied on matte paintings to extend or flesh out the background. This is perhaps my favourite matte painting, from the end credits of Die Hard 2:

Turns out, videogames do something similar, except the result is called a skybox, since it has to encompass the player from all sides. It’s another way to use cheap trickery to pretend the world is larger than it is.

This 9-minute video by 3kliksphilip shows a few more advanced skybox tricks from Counter Strike games using the Source engine:

I particularly liked two discoveries:

• In real world, you wouldn’t style backfacing parts, because the player will never be allowed to see from the other side. Here, you don’t even have to render them.
• Modern skyboxes have layers and layers of deceptions: more realistic 3D buildings closer to you, and completely flat bitmaps far away. It almost feels like each skybox contains the history of skybox technology that preceded it.

On the other hand, seeing clouds as flat bitmaps was really disappointing.